A woman went to a magician but she did not know that this is impermissible. Now she fears that what she did out of ignorance when she was young will be added to her bad deeds.

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

If a person does a prohibited act out of ignorance, he is not sinful but he may be a sinner if he had the ability to learn but did not. Ibn ‘Abbaas narrated that a man gave the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, wine as a gift. When the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, asked him whether he knew that Allaah prohibited wine, the man said, "No." [Muslim]

Allaah Says (what means): {And never would We punish until We sent a messenger.}[Quran 17:15]

However, if a person has the ability to learn but fails to do so, he is sinful.   This woman should not have done anything before asking about the religious ruling about it. Anyway, if a person repents to Allaah, Allaah will accept his repentance.

Allaah Knows best.