What should I do to solve the problem of my many debts, the owners and amounts of which I do not remember, and when can I perform Hajj without these debts affecting the validity of my Hajj?

You must strive to repay the debts you are aware of. If someone demands payment from you and has proof, or if you recall owing them money, then pay them back. If you know the amount of a debt but cannot find its owner, then give that amount in charity on their behalf. If the owner later appears, give them the choice between the reward of the charity or having their debt repaid to them. As for Hajj, you can perform Hajj after repaying your debts to those you know, or you may seek their permission before going for Hajj.