Trouble w/ Organizer

Here is my problem: When I download photos from my camera, the organizer assigns a name to the new file and I can see it added to the long list of files on the left. I right clicked on the file to rename it; then I moved the cursor up to a different file and left clicked on it( I don't think I double clicked but I could have by mistake). A block popped up that said it would take 4 min. to copy files- I had never seen this block. When block went away, it had put 11,000 photos( 52 gig) into my last file that I had just renamed. I have probably a 150 to 200 files above this one and the photos were removed from all of them. How do I undo this mess?

Not sure but can you just backup or do not save and start over?