i have itunes signed up on my iphone and nothing else. i signed into my friends itunes account and then resigned into mine. now its not letting me download any of ky music for 90 day... is there a way i can get around that on my phone?

When you log into an account and use iTunes Match, automatic downloads or redownload past purchases then you are likely to start a 90 day association on that computer or device - I think that it's an attempt to try and stop people signing into their account's on other people's computers and sharing their purchases. If you can't wait until the 90 days have completed then you can try contacting iTunes Support and see if they can remove the association : http://www.apple.com/support/itunes/contact/

Associating a computer or device : http://support.apple.com/kb/HT4627