Just disconnecting it without ejecting should not cause permanent damage. It may cause data corruption, if iTunes was in the process of syncing at the time. But iTunes should still see the shuffle and (maybe) tell you to Restore it.
Is it possible that the "accident" damaged the USB cable?
Make sure you have done this on the shuffle since the problem occurred
And you should also shut down (power off) the computer, if you have not already.
Have you tried more than one USB port on the computer (not a hub if you use one)? You can also try it with all other USB devices disconnected, except for standard keyboard and mouse (if normally used).
If those things do not help, what version of Windows do you use?