How can one achieve sincere repentance, correct prayer, purify the heart, and get rid of obsessive thoughts and vile ideas after falling into watching pornography, masturbating, and listening to music, especially when experiencing difficulty concentrating in prayer and having ablution affected by obsessive thoughts and doubts about bodily purity?

Repentance from sins involves immediately abandoning them, resolving not to return to them, and regretting having committed them. As for intrusive thoughts (waswas), their cure is to ignore them and pay them no mind. If you doubt whether an impurity has afflicted something, the original state is its absence, and if you have washed it, then assume its removal. The path to righteousness is achieved by observing the obligatory duties, increasing supererogatory acts, attending gatherings of knowledge and remembrance (dhikr), learning the rulings of the Sharia, associating with good people, avoiding bad company, frequently contemplating death, Paradise, and Hellfire, reflecting on Allah’s names and attributes, reciting the Quran with contemplation, along with striving diligently in supplication.