Is it possible for one to repent and be forgiven for multiple sins such as repeated abortions, theft, committing immoral acts, giving birth to a child out of wedlock, and pursuing a career in dancing, knowing that one is unable to restore the rights of those wronged due to ignorance of their whereabouts, and how does one fast for the atonement of abortion?

You must repent to Allah with sincere repentance, abandon all sins, and regret what you have committed. As for expiation for abortion, there is a difference of opinion regarding its obligation. Where expiation is deemed obligatory, you must fast for two consecutive months for each fetus you aborted if human creation was discernible in it. As for the stolen money, you must give it as charity on behalf of its owners whom you do not know. If you are sincerely repentant and in need of this money, you may give it as charity to yourself. As for those whom you know, you must return their rights to them or seek their forgiveness without informing them of the theft. What you are unable to do, you must fulfill your obligation when you are able. And increase your prayers for forgiveness, good deeds that efface sins, and supererogatory acts of worship, and associate with righteous people.