Try ctrl-Z followed by
<return> - that will put the current process into the background, and you should get your terminal back.
should list your current background jobs. You can bring a job back to the foreground by typing
where n is the job number listed by the jobs command.
ctrl-C should interrupt your current process.
There are probably some places where ctrl-Z means something to the program . . . so to be safe you probably need to know what it is that has caused you to get trapped . . .
I think this should probably work in most shells - certainly bash and tcsh. If you're using something else YMMV.
Good luck. It's worth the learning curve.