I did the same a while ago if you look in the G2 forums... I used ES File Explorer to screw it up and with my luck I didn't have it set to back up deleted files to a recycle folder so I was basically screwed and had no way to fix it so I had to either use awful third party apps to replace what I jacked up or flash a custom ROM. Currently on sokp...
If you go into your file manager settings you should see a recycle bin option I recommend enabling that so that maybe you can restore it or if you accidentally do something again it won't be gone forever.