if someone has hacked your account they may have already changed the password
have you tried the 'Password reminder' option on the RapidShare site?
(that should send 'You' the current password to the email address you registered with RapidShare - unless they (the hacker) can also change that?)
Only other thing I can suggest is to keep contacting RapidShare and plead your innocents (this must happen quite a lot - it doesn't take much to guess someones username & password)
good luck