It probably got stopped halfway through making the change, so it moved the original icons but didn't get around to putting in the new ones. You may be able to restore the originals.
EDIT: Ignore the part here about the Finder.app, you need to look in Dock.app for both icons you want to change. I'll leave it in case someone else needs those instructions.
In the Finder, go to /System/Library/CoreServices/
Right click on Finder.app and choose "Show Package Contents."
Go to Contents/Resources/ and look for a file that was previously called Finder.icns (I believe CandyBar renames it to Finder Backup.icns, or something of the sort). Rename it to Finder.icns, assuming it appears to be the correct icon (you can QuickLook it to make sure it's the right one).
Then go back to the CoreServices folder and repeat the process with Dock.app, this time looking for two files: trashempty.png and trashfull.png. Again, they've probably been renamed. Just change the names back to the correct ones.
Then in the Terminal put in the "killall -HUP Dock" command, and they should be back.
If not, you'll have to try to get those original images from somewhere. PM me if you need them.
jW
