What can I do for God to answer my prayers, to regain my trust in everything, and to overcome the state of pessimism that has afflicted me? And do you have a prayer that is answered that can help me?

We advise the questioner to avoid pessimism and to be content with Allah's decree, for what a servant considers good may in fact be evil. As for supplications (du'as), there are comprehensive ones, including: "O Ever-Living, O Sustainer! In Your mercy I seek assistance; rectify all my affairs and do not abandon me to myself for the blink of an eye," and "O Allah, there is no ease except that which You make easy, and You make sorrow easy if You wish," and "O Allah, guide me and make me steadfast." We pray to Allah to rectify the questioner's affairs and warn him against despair and haste in supplication.