Recovered Photos Are Thumbnails Only

Our computer recently had a hard drive that we reformatted over to clean install the operating system. We, however, horribly failed to check to see if our photos were secure before we reformatted the drive. So, I got a photo recovery software and managed to get them all back, however they are only thumbnails.

I literally recovered 132,000 photos (Only 17,000 of which are actual photos I took, the rest of random image files the software grabbed) and not one of these photos is normal sized. They are all thumbnails. Is there any way to fix this? All these photos are useless to me as thumbnails