Those who aren't touch typists may find you look at the keyboard rather than the screen when typing.

If so, you may have accidently typed Qwerty keys when your computer was in Colmak mode, or vice versa, resulting in gibberish.

You can, of course just retype. But if it's a long enough string of gibberish, you may want a program that converts the mistyping.

You can get the source code for such a program here:
http://www.diffenbach.org/convertColmak.cpp