Would need to find out more about what's wrong with it, but there's a geared transmission on each side driven by a single motor. On the old type transmissions it's possible for the gears to run past the end of their travel and 'come off' the drive, might be as simple as disconnecting the cables that drive the gears from the motor and running them backwards with a hand drill until they pick up the gears again... or it could be a lot more difficult... all depends on what's up really.
You could start by reading through some of the info here to get a better idea of how it works...
https://sites.google.com/site/mikefocke2/thetop-itsmaintaince%26replacement
Porsche Boxster Convertible Top Repair - 986 / 987 (1997-08) - Pelican Parts Technical Article
...then add more info when you bring it home.