What should a repentant woman do who stole a lot of money and property from people she doesn't remember, nor does she remember the amount she stole?

All praise is due to Allah, who guided the questioner to repent from theft, which is a great sin and a major transgression, and a compound offense involving both the rights of Allah and the rights of people. If she is unaware of the rightful owners and the exact amount, she should give in charity what she believes will clear her conscience regarding the rights of the owners. Then, if the rightful owner is found later, he has the choice between accepting the reward of the charity or being given his right, in which case the reward of the charity will be hers.