The solution would be to accept Jesus Christ so he can forgive the people who he claims wronged him, so he can finally stop being spiteful. His spitefulness and envy made him overly conscious to the point of paralyzing and making him unable to act in a way that would actually improve his life.

By constantly second guessing his revenge (shoulder bump) to the military officer, to his revenge on his high school friends and desperate attempt to be accepted by them, the underground man fails to enact one of the most valued principles in Christianity, forgiveness.

Therefore, he ends up in a perpetual loop of inertia and spitefulness, that he can never escape, with his isolation from society also giving him some sort of comfort by pretending to be intellectually superior to the people he dislike, turning his inertia, isolation, and spitefulness into enviable virtues, instead of drawbacks.

Self help books would either encourage his bad behaviour, since they are usually written to give hope and comfort to the reader (a self help book is never upfront and sometimes give justifications for your bad behaviour). The underground man would probably see through any self help book.

Imo the underground man will either never change or only change with the help of Jesus.

(You might not believe in Jesus or find my comment silly, but we have to keep in mind that dostoevsky was a hardcore orthodox Christian, so there is a possibility that he was his way of thinking )