No really easy fix you can do yourself, as the mechanism inside the cassette can be very fiddly and awkward to work with. Unless you have experience, opening the case will likely result in a wrecked tape.
If it's simply the opaque leader that has seperated from the spool it is repairable and there are several people offering this service on the internet. You may even find someone locally to carry out the repair.
Try camera stores or photographic services, sometimes they will do this type of work or transfer video from one format to another etc.
Cobweb, December 2004