I'm a bit puzzled by what you could have done. OK, fine, you copied something. Copying something should leave the original untouched, so you must have cut, not copied, or nothing would have vanished.
Hitting undo at that point should have stepped you back before the copy and everything should have been fine.
Then you say, "when I brought it back up, it appeared to be in raw data." What do you mean, "brought it back up?" Did you close the file and save the messed-up state, then re-open it? Ouch. And what do you mean by, "it appeared to be in raw data?" If you copy part of a sound file, it is raw data. SO maybe you can explain what you did a little more clearly?