Hi Barbara.
Depending on how your cassette is held together and how the spool holds the tape in place, your repair might take one of a few different routes. If the halves of the cassette body are held together with screws, remove them with a small screwdriver--they should be in each of the four corners, and maybe one in the center at the bottom. If the halves are glued together, you'll have to either do your best to break the glue at the seams so you can re-glue or tape together the halves of the cassette when you're done, or try to find a cheap screw-together cassette at a 99-cent store or the like to use as a replacement housing for the tape. Either way, be sure to lay the cassette down flat while you work on it so that the pieces stay in place when you separate the halves--it's a pain to get all the little wheels and the little guide bar thing back in place if they get knocked out.
From there, you'll want to take a look at the spools themselves. Usually, the tape is either glued to the spool, or it is pressure-fitted into a little detachable segment of the spool (about 1/5 of the spool). If it's the glue type (or even if it isn't and you just want to reattach the tape this way), simply reattach the end of the tape to the spool using either Krazy glue (be careful not to glue your fingers to it!) or a small piece of scotch tape. If you go the scotch tape route, be sure to wrap some of it on the side of the spool to hold the cassette tape in place. Otherwise, it'll just slip out when you rewind the tape. If it's the pressure-fit kind, remove the segment and slide a bit of the casette tape into the wedge-shaped hole. Then hold it there while you re-attach the little piece of the spool. If all else fails, you may want to consider buying another copy of the tape.
'Hope that helps. Happy repairing.
Jeff Wisdom, August 2005