How can I repent and return the money I stole, given my inability to work or borrow, and my desire for marriage and chastity?

It is advisable to continue searching for a permissible job. As for people's money, it is a debt owed until it is paid, unless its owners waive it. There must be a firm intention to repay it, along with supplication and seeking forgiveness. If the amount of money is unknown, one should strive to estimate it in a way that clears the conscience. What is unknown regarding its owners should be given as charity on their behalf.