Powerful Dua for Forgiveness in Islam
Question

I have been a great sinner before. I did not read my salat often enough, did not make Dhikr, read durood,etc.
Recently, I experienced some misfortune in my life and I have only myself to blame. This misfortune has opened my eyes in many ways and I have started a complete turn-around of my previous lifestyle. I need to know if there is anything I may read daily to become closer to The Almighty and really focus on doing good to wipe out the evils/sins of my previous lifestyle. Are there things I may read while I am working too?
Praise be to Allah.The Importance of Seeking Forgiveness of Allah
All praise be to Allah for the great blessing which He has bestowed upon you by guiding you to the way of truth after you had been astray, and for your return to Him after you had been a sinner, neglecting His laws. We ask Him, may He be Glorified, to complete His favour upon you by guiding you further and making you adhere steadfastly to His religion. As regards what you should do about your past and how you can make up for what you have missed, you will find detailed answers in the book “..”I Want to Repent, But…”,
Daily Du`a for Forgiveness in Islam
With regard to Du`as to do with repentance that you can recite every day and whilst at work, Al-hamdulillah there are many such Du`as, among the greatest of which are as follows:

“Rabbighfir warham wa anta khayrur-rahimin (My Lord! Forgive and show mercy, for You are the Best of those who show mercy!)” [Al-Mu’minun 23:118 – interpretation of the meaning].
“Rabbana ighfir lana dhunubana wa israfana fi amrina (Our Lord! Forgive us our sins and transgressions (in keeping our duties to You).” [Al `Imran 3:147 – interpretation of the meaning]


Shaddad ibn Aws (may Allah be pleased with him) reported that the Prophet (peace and blessings of Allah be upon him) said: “The best prayer for seeking forgiveness is to say: ‘Allahumma anta rabbi la ilaha illa anta, Khalaqtani wa ana `abduka wa ana `ala `ahdika wa wa`dika ma astata`t. A`udhu bika min sharri ma sana`tu, abu’u laka bi ni`matika `alayya wa abu’u laka bi dhanbi, faghfir li fa innahu la yaghfirudh-dhunub illa anta (O Allah, You are my Lord. None has the right to be worshipped but You. You created me and I am Your slave, and I am faithful to my covenant and my promise (to You) as much as I can. I seek refuge with You from all the evil I have done. I acknowledge before You all the blessings You have bestowed upon me, and I confess to You all my sins. So I entreat You to forgive my sins, for nobody can forgive sins except You).” Whoever says this during the day, having faith in it and dies before the evening comes, will be among the people of Paradise, and whoever says it during the night, having faith in it, and dies before the morning comes, will be among the people of Paradise.” (Narrated by Al-Bukhari, 5831)
Abu Musa (may Allah be pleased with him) reported that the Prophet (peace and blessings of Allah be upon him) used to recite the following Du`a: “Allahumma ighfir li khati’ati wa jahli wa israfi fi amri wa ma anta a`lam bihi minni. Allahumma ighfir li jiddi wa hazli wa khata’i wa `amdi wa kullu dhalika `indi. Allahumma ighfir li ma qaddamtu wa ma ajjartu wa ma asrartu wa ma a`lamtu wa ma anta a`lam bihi minni. Antal-muqaddim wa antal-mu’akhkhir wa anta `ala kulli shay’in qadir ( Allah, forgive me for my sin. My ignorance and my transgression (in keeping my duty to You), and whatever You know about me better than I do. O Allah, forgive me for sins committed in earnest and in jest, by mistake and deliberately, and I have done all of that. O Allah, forgive me for what I have done in the past and what I will do in the future, what I have done in secret and what I have done openly, and whatever You know about me better than I do. You are the One Who raises and lowers people’s status, and You are Able to do all things).” (Narrated by Al-Bukhari, 5919 and Muslim, 4896. This version was narrated by Muslim).
Ibn `Umar (may Allah be pleased with him) reported that the people counted for the Messenger of Allah (peace and blessings of Allah be upon him) when he recited one hundred times in one gathering: “Rabighfir li wa tubb `alayya innaka antat-tawwab ul-ghafur (My Lord, forgive me and accept my repentance, for You are the Acceptor of Repentance, the All-Forgiving).” (Narrated by At-Tirmidhi, 3356. He said, This is an authentic Hadith).

For more details, please see the following answers:
How to Repent in Islam
Conditions of Repentance
Salat At-Tawbah (Prayer of Repentance)
The difference between repentance and forgiveness
Impact of prayer for forgiveness (Istighfar) on receiving a response to supplication (Du`a’)
Seeking Forgiveness is a Means of Strengthening the Body
And Allah knows best.