If the tape breaks near one end:
Open the cassette, unwind and through away the small side of the tape. On the now enpty roller you should be able to open the plastic clamp that holds the tape with a small screwdriver. Put the end of the big side of the tape into the clam and carefully clam it shut.
If the tape breaks in the middle:
Use scotch tape to tape the two ends together (wrap around once.
Use a tape to tape recorder to retape your broken tape to a good tape (the song on the break may not be usable).
Throw away the broken tape.
