well she came back in season 5 when brooke went to new york with owen.
they found her in brooke's aparment. she had taken an overdose of drugs.
owen managed to wake her up and she didn't want to go to rehab so brooke took her home.
she was doing fine untill brooke and peyton we out one night and victoria (brooke's mum) came in and started telling her she was no good for anything.
so rachel stole some money and left.

:)

yea pretty much what loves-oth said...she really just had a few scenes.