Can You Pray With Urine on Clothes?
Question

What is the ruling if some drops of urine get in the under pants while urinating normally or in a hurry.
1. Is Ghusl needed to purify yourself? 
2. Do you have to wash the whole underpants or always change it or wash only the parts on which there is urine?  
3. How to pray in this condition? Is the prayer valid if you pray?  
4. What if there are some doubts where the drop has fallen and  is not washed? Will it affect the prayers and purity?  
5. Should he repeat his prayers ? Is reading or handling the Quran allowed?
6. What things are prohibited in this case? 
Hope you clear my doubts with clear fatwas.
Praise be to Allah.The obligation of removing impurity
The Muslim must beware of impurity and try to avoid it as much as he can. Ibn `Abbas (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) passed by two graves and said, “They are being punished, but they are not being punished for something that was difficult to avoid. One of them used to walk about spreading malicious gossip, and the other used not to take care to avoid getting urine on himself.” (Narrated by Muslim, At-Taharah, 439) 
What is meant is that he did not take precautions to avoid getting it on himself. Hence it is permissible to urinate standing up so long as a person can be sure that he will not get splashes of urine on his clothes or his body. 
Secondly, with regard to the points raised in the question: 
Is Ghusl required if Najasah gets on your clothes?
If Najasah gets onto a person’s clothes, he does not have to do Ghusl, because Najasah is not one of the things that invalidate Wudu’ or Ghusl . Rather Ghusl is required in the case of major impurity and Wudu’ is required in the case of minor impurity. But what he has to do in this case is to remove the Najasah. 
We are commanded to remove impurity from our clothes because Allah says (interpretation of the meaning): 
“And purify your garments.” [Al-Muddaththir 74:4]
The Prophet (peace and blessings of Allah be upon him) said, concerning menstrual blood that gets on the clothes, “Take hold of the soiled place, rub it and put it in water and rub it in order to remove the traces of blood and then pour water over it. Then pray in it.” 
If Najasah gets onto something that can be wrung out, then this is what must be done. 
How to remove impurity
Removing the impurity may be done by washing it until the traces of the impurity have disappeared. So if the Najasah gets onto his clothes, he only has to wash the part of the garment where the impurity is, and he does not have to wash the rest of it. Also, he does not have to change his clothes, but if he wants to change his clothes, there is nothing wrong with him doing that. 
Can you pray in a garment that has some impurity? 
With regard to the ruling on praying in a garment on which there is some impurity , it should be noted that being pure and free from Najasah is a condition of the prayer being valid, and if a person is not free from impurity then his prayer is invalid, because he prayed when he was contaminated with this impurity. So if he prays when he is contaminated with impurity then he has prayed in a manner that is not enjoined by Allah and His Messenger. It was narrated that the Prophet (peace and blessings of Allah be upon him) said: “Whoever does an action that is not part of this matter of ours (i.e., Islam), will have it rejected.” 
When impurities get onto clothes, one of the following scenarios must apply: 

When a person is certain that impurity has gotten onto a particular part of his garment, in which case he must wash the area where the impurity is.
When he thinks it most likely that the impurity is on a particular part of the garment.
When a person thinks that there may be some impurity in some part of the garment. In the second and third cases, he should make a decision, and whatever part of the garment he thinks is affected by the Najasah, he must wash it. (See Ash-Sharh Al-Mumti’ by Ibn ‘Uthaymin, 2/221) 

Ruling on a small amount of impurity
Some of the scholars said that a small amount of impurity cannot be overlooked at all.  
However, some of them said that a small amount of all types of impurity may be overlooked. This is the view of Abu Hanifah and was the view favoured by Shaykh Al-Islam Ibn Taymiyyah, especially with regard to problems that many people face, because it is too difficult to be thorough and to clean it properly all the time. Allah says (interpretation of the meaning): 
“and [Allah] has not laid upon you in religion any hardship.” [Al-Hajj 22:78]
The correct view is the view of Abu Hanifah and Ibn Taymiyyah. Among the small amounts of impurity that may be overlooked because it is too difficult to guard against it is a small amount of urine in the case of one who suffers from incontinence but tries to guard against it as much as he can. (See Ash-Sharh al-Mumti’ by Ibn ‘Uthaymien, 1/382) 
With regard to what constitutes a small amount, whatever ordinary people consider to be a lot is a lot, and whatever they consider to be a little is a little.  
On this basis, it may be said that the basic principle is that if a few drops of urine get on a person’s garment and he washes off whatever got on it, until he thinks it most likely that the Najasah has disappeared, then whatever is left and is not washed comes under the heading of the small amount of Najasah that may be overlooked, as stated above. And Allah knows best. 
Ruling on not being aware of impurity
Shaykh Ibn Baz was asked about the case of one who is unaware of the Najasah . He said: 
If he does not find out that it is impure until after he has finished praying, then his prayer is valid, because when the Prophet (peace and blessings of Allah be upon him) was told by Jibril while he was praying that there was something impure on his shoe, he did not repeat the first part of his prayer. The same applies if he knows about it (i.e., the impurity) before he prays, then he forgets and prays wearing (the garment with the impurity), and does not remember until after he has finished praying, because Allah says (interpretation of the meaning): 
“Our Lord! Punish us not if we forget or fall into error.” [Al-Baqarah 2: 286]
But if he has some doubts while praying as to whether there is some impurity on his clothes, it is not permissible for him to stop praying, whether he is leading the prayers or is praying alone; he must complete his prayer. (Fatawa Ash-Shaykh Ibn Baz, 12/396-397) 
Doubts about impurity
The issue of not being sure whether the impurity has been removed: if he gets some impurity on his clothes then this is the certain fact and this certainty will remain until the impurity is removed. Then if he is not sure whether he has removed the impurity or not, he should go by that which is certain, which is that he has not yet removed the impurity. The converse also applies, if he is certain that his clothes are pure, then he becomes unsure whether something impure got onto them or not, he should go by that which is certain, which is that his clothes are pure because that is what he is certain of. 
Shaykh Ibn ‘Uthaymin said: 
“With regard to a person’s clothes, the basic principle is that they are pure so long as he is not certain that some impurity has gotten onto his body or clothes. This basic principle is supported by what the Prophet (peace and blessings of Allah be upon him) said when a man complained to him that something happened to him during his prayer – i.e., he invalidated his Wudu’. The Prophet (peace and blessings of Allah be upon him) said to him: “Do not stop praying unless you hear a sound or detect a smell.” If a person is not sure about it, then the basic principle is that he is pure. A person may think it is more likely that his clothes have become contaminated with Najasah but so long as he is not certain, the basic principle is that they remain pure.” (Fatawa Ibn ‘Uthaymin, 11/107) 
The only thing that is not permissible if a person has Najasah on his clothes is prayer, even if he has not invalidated his Wudu’. Other actions such as reading the Quran etc. are not prohibited. 
And Allah knows best.