How can i fix my cassette player?

I have a 1998 Oldsmobile 88 LS and the cassette player continually displays the error message E10. I bought another cassette and the message continues to appear even though there is nothing wrong with the new cassette. the cassettes are actually MP3 player converters that play music from an ipod or CD player through a cassette player. It was working before until my friends decided to mess with the radio and press buttons. Can someone help?

Stephon W.
March 2011