Desperately need my SD card images back

Put the card in your PC and try Recuva to recover those photo's. It's a free download.

More in http://www.cnet.com/how-to/how-to-recover-deleted-photos-from-a-memory-card/

Kees

Yes, there are ways for you to recover your deleted SD card image folder back. Just stop suing this SD card and keep it away from any new photo or file. And then, see whether all your images could be restored with data recovery software.
Read this post and see whether listed answers could give you some clues of card photo recovery:
http://forums.cnet.com/7723-19411_102-625379/rescue-deleted-files-from-windows-7-computer/?tag=StickyWin_1408608545817;createThreadPopup

There are many programs out there to do this, some of the sansdisk cards come with this software, so you may go buy a new card to get it. You can use the new card for backup, something that sounds like you tried, but it failed. One of the best free programs I have used is pci smart recover,
http://pc-inspector-smart-recovery.en.softonic.com/ It has even recovered from card that were formatted and some that were damaged.
As other's have stated, do not use or do anything with this card until you have loaded the software and are ready to recover the files. And as you well know now, if its important, do at least 3 back ups, EVERYTHING FAILS.
I put mine on a external hard drive, on a thumb drive, and I now use M-disc. Its a form of dvd that is suppose to last 1000 years, you have to have a new burner, but they are cheap, and the disc are about 3.00 for dvd. Regular dvds will fail in several years. I have had some fail in as little as a year, but some are still working after 8 yrs. A lot depends on the quality of the disc and the storage environment. The M-disc is suppose to be fairly immune to most of this.
ps, I take my backup thumb drive to work to store, this way, if the house is ever broken into, burns, hurricane or whatever, at least I have a copy at a different location.

You can definitely try some software, or go to a store that specializes in it. Staples comes to mind as a service that can help you.

That's why one is suggested to save data backups on several devices or locations. So, just remind yourself to abide that principle in the future.
But, now, insert this SD card to computer and download data recovery software to see whether your deleted imaged folder could be rescued. Start this application, deep Scan your card, preview and restore all needed photos back. And then, rightly use this SD card from now on and always prepare data backups well!
Here is a video tutorial that may let you know more detailed stuffs:
https://www.youtube.com/watch?v=AX5kNLKKJcg
Hope my words can help you somehow.