Can Muslims be affected by psychological problems?
Question

Is it possible for a Muslim to be afflicted with psychological problems? (Because some people say that a Muslim cannot be affected by psychological problems).
Praise be to Allah.Undoubtedly man may be afflicted with psychological problems such as worries about the future and grief over the past. Psychological problems affect the body more than physical problems do. We should know that the worries and distress that affect a person are among the things that expiate his sins and reduce the burden of sin; if he is patient and seeks reward with Allaah, he will be rewarded for that. 
Treating these problems in the ways prescribed in Islam is more effective than treating them with physical medicine, as is well known. 
One of the treatments prescribed in Islam is to recite the du’aa’s narrated from the Prophet (peace and blessings of Allaah be upon him) to relieve worries and distress, for example, the saheeh hadeeth narrated from Ibn Mas’ood (may Allaah be pleased with him): “There is no-one who is afflicted by distress and grief, and says: ‘Allaahumma inni ‘abduka ibn ‘abdika ibn amatija naasyati bi yadika, maada fiyya hukmuka, ‘adlun fiyya qadaa’uka. As’aluka bi kulli ismin huwa laka sammayta bihi nafsaka aw anzaltahu fi kitaabika aw ‘allamtahu ahadan min khalqika aw ista’tharta bihi fi ‘ilm il-ghayb ‘indaka an taj’al al-Qur’aana al-‘Azeema rabee’ qalbi wa noor sadri wa jalaa’ huzni wa dhihaab hammi (O Allaah, I am Your slave, son of Your slave, son of Your maidservant; my forelock is in Your hand, Your command over me is forever executed and Your decree over me is just. I ask You by every name belonging to You which You have named Yourself with, or revealed in Your Book, or You taught to any of Your creation, or You have preserved in the knowledge of the Unseen with You, that You make the Holy Qur’aan the life of my heart and the light of my breast, and a departure for my sorrow and a release for my anxiety),’ but Allaah will take away his distress and grief.” This is one of the remedies prescribed in sharee’ah. One may also say: “Laa ilaaha illa anta, subhaanaka inni kuntu min al-zaalimeen (There is no god but You, glorified (and exalted) are You, truly I have been of the wrongdoers).” [cf. al-Anbiya’ 21:87] 
Another form of treatment is ruqya with which a person may treat himself – which is better. The Messenger (peace and blessings of Allaah be upon him) used to do ruqyah for himself by reciting al-Mi’wadhatayn (the last two soorahs of the Qur’aan) when he went to sleep, then he would wipe his face and whatever he could of his body. Or a person may go to someone whose religious commitment he trusts to do ruqyah for him. 
If he wants to know more, he can refer to what the scholars have written about du’aa’ such as al-Waabil al-Sayyib by Ibn al-Qayyim, al-Kalim al-Tayyib by Shaykh al-Islam, al-Adhkaar by al-Nawawi, and Zaad al-Ma’aad by Ibn al-Qayyim. 
From the fatwas of al-Shaykh Ibn ‘Uthaymeen, Kitaab Fataawa Islamiyyah, vol. 4, p. 465-467.