What is the way to overcome shortcomings in performing prayers and fasting, listening to music, feeling despair regarding the acceptance of good deeds, and ignorance of religious matters?

To pinpoint the issue with your negligence in prayer, you must realize that it lies within yourself, and the help of others will not benefit you until you take yourself to salvation. The feelings you mentioned indicate the presence of the foundations for righteousness and piety, but you must overcome the weakness of self-control. Prayer is a mercy ordained upon us by Allah, and whoever preserves it will witness Allah's favor and know that the truly deprived person is the one who deprives themselves of the sweetness of connection with Allah. You must find within yourself a great concern and immense eagerness to preserve your prayers, and endeavor to immediately stand for prayer upon hearing the call to prayer (adhan). Ask Allah for help in remembering Him, thanking Him, and worshipping Him beautifully. Be diligent in associating with righteous girls and ask them for help, and beware of sins, for they weigh down a servant from their prayers. As for doubt concerning the Ramadan fast, do not pay attention to doubts after completing the act of worship if your predominant thought is that you performed it. However, if there was indeed aترك (ترك - omission/abandonment), then repentance, seeking forgiveness, and making up the missed fasts are obligatory.