What should a disobedient son do, whose mother has cursed him with failure in this world and the hereafter, and who has despaired of his life and ceased performing good deeds and striving?

If the mother is alive, the questioner must repent and strive to appease her and show her piety. If she is deceased, he must repent and frequently supplicate, seek forgiveness, give charity on her behalf, maintain ties with her relatives, and be good to her friends. As for the questioner's abandonment of prayer and studying due to the mother's supplication, this is from the whisperings of Satan, because despairing of Allah's mercy is a characteristic of disbelievers, and Allah accepts the repentance of those who repent.