How can one deal with severe mood swings that lead to abandoning acts of worship, feeling despair and unworthiness of drawing near to Allah, and fearing committing future follies?

It is recommended to seek refuge in Allah and to pray for steadfastness in truth. It is also important to know that self-reproach for shortcomings is a sign of goodness, and that a believer reproaches himself, while a wicked person proceeds without accountability.

The immediate initiation of sincere repentance with its conditions is required. If the soul weakens and returns to sin, one should not despair, but rather renew repentance and not surrender to the whispers of Satan, as evidenced by the Almighty's saying: "And never give up hope of Allah’s mercy. Certainly, no one despairs of Allah’s mercy, except the people who disbelieve."

The noble Hadith is also mentioned about the servant who sins and then seeks forgiveness, and Allah forgives him, with the caveat that repeated sins and repentance are acceptable. The saying "Do what you wish" means that as long as you sin and repent, you will be forgiven. This is not a license to sin, but rather an indication of the vastness of Allah's mercy and an encouragement to repent.

It is also advised to be keen on everything that aids guidance and righteousness and to stay away from what leads to misguidance. Missed prayers must be made up.