What is the ruling on the obsessive thoughts a young man has been suffering from for years regarding multiple matters such as cleanliness, which have developed into doubts about memories and acts of worship, affecting his life and studies, and he is unable to consult a psychiatrist or take medication?

A Muslim should not surrender to intrusive thoughts (waswas), as they are from the plots of Satan. Among the best ways to get rid of them are: being convinced that they are following Satan, and completely ignoring them. When one does not pay attention to them, they disappear.

Intrusive thoughts are an innovation, rooted either in ignorance of the Sunnah (definition) or in mental instability. Ignoring them is the solution. A Muslim should seek refuge with Allah from the accursed Satan, supplicate to Allah, and remember the vastness of Allah's mercy, and that religion is ease.