Is the distress and change in his life that befell the young man due to the sins and acts of disobedience he committed, and how can he restore his normal life and his devotion in prayer?

It is recommended to sincerely repent to Allah Almighty for sins. If a servant repents with true repentance, Allah will forgive their sins, and they will be as if they had not sinned, in accordance with His saying, the Exalted: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful'," and the saying of the Prophet, peace and blessings be upon him: "The one who repents from sin is like one who has no sin."

As for calamities, one should be patient and seek reward from Allah, and know that what has befallen them is a decree from Allah, and that "No disaster strikes except by permission of Allah. And whoever believes in Allah - He will guide his heart." So, the believer accepts and submits to Allah's decree.

One should be content with Allah's decree, have good expectations of Him, rely on Him in all matters, and seek His help to attain benefits and ward off harms, while taking worldly means. It is also advised to consult a trustworthy psychiatrist for psychological problems.