How can one return to religious commitment and overcome desires and temptations in infidel countries, given the unavailability of religious books for reading?

What happened to you may be due to living in lands of immorality and bad company. The cure for this is to move away from them immediately, as soon as possible, and to avoid bad company, replacing them with righteous companions. The path back to Allah is made easy through sincere and truthful repentance, for the one who repents from a sin is like one who has committed no sin. Allah Almighty says: "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.'" You must hasten to repent and return to Allah to find happiness and tranquility. The absence of religious books should not deter you, as they can be obtained or replaced by religious websites.