From the backup of your images stored on another medium like CD or USB hard
drive.
Now, since you don't have those backups (or you would not be asking here)
stop using the machine where the files were stored. Go to another machine
and Google and download one of the many free file undelete programs and put
it on a USB disk or CD. Run the program on the computer where the missing
folder is located and see if it can recover the deleted files.
The reason I say to stop using the computer is that every time you access a
file, open a program or even download emails you stand the chance of
overwriting the location that the deleted files were stored on the hard
drive. Deleted files are not removed physically from the drive, the
physical location is only given back to the operating system as available to
be written to.