How to recover my worlds in Minecraft?

I've downgraded lots in the past with minecraft, and today i decided to do it again, only i realized i couldnt because of the new launcher, so, i took the beta bin out of my.minecraft folder and put back in my regular bin, only one problem, i lost all my worlds! I tried using all my back up bins on my computer to make sure i didn't use a blank bin on accident, but all of them were blank. I went to my saves folder to try to restore earlier saves from the past, but they were from the saves after this happened. What do i do?