Hi. A shot in the dark here that so done might be able to answer. Wife asked me to transfer pics from her Android phone (Motorola) so I USB'd it over (cut and paste). The total was around 1000 files at 15.1gb.
All files went, so not on phone now. We cannot open a single one. But here is the locker. It shows that EVERY individual file is 15.1 GB and that the folder is 17TB! I haven't had that much HD space on all the computers I have owned in my entire life combined.
First I have to ask if the images were in say a locked folder or file on the phone? Sometimes that will cause them to show incorrectly when you move them.
If not, then I would suggest you first try rebooting the computer. Power it off and back on. Sometimes that is all you need. Should they still not show correctly, then I would be looking at them to make sure they are actually named correctly. Some phones, while they are actual JPG files, don't correctly name the files, adding the extension. So take a single file and try renaming it to see if this fixes it.
If you still can't access them then I would suggest one of the following. 1. Move them all back to the phone and see if they show correctly on there. If they do, then you may need to move them a different way onto the computer. Making sure there is nothing on the phone that blocks them. Or you can try using a program like 'Format Factory' (it is free) and use it to convert the files (start with just one or two) and see if this resolves it. If you choose the conversion option, just make sure in the programs settings that you set it to save the converted files in a new folder, this way you don't alter the original files. Just in case.
I will look at some of the stuff you said, though have tried putting files back on the phone. Problem is, like I mentioned, now each file (all 1000 of them) are showing a size of 15.1gb, with a culmalative size of 17TB. The files don't seem to want to go back over.
Something the must have altered them in the transfer. They can't just multiply in size. Not unless perhaps.... did it change them into ZIP files when moved? Or another form of compression. If all the files were zipped up, compressed, into singular files, then each may actually contain all the images, then there would be repeated versions of the same file. If that is what occurred, then you have all the files that many times over.
However, that would take up a serious amount of space on the computer, making it very unlikely. A way to check the sizing for sure would be to right click on the folder that they are in (from outside the folder) and check the size of it. Most laptops don't have that much room on them, not even most desktops, so it is likely something is giving a false reading.
Sounds like the files are corrupt, no real way to sort out how that happened though. You did what a lot of people do when they go to forums to get help with lost files, you moved the files instead of copy them, and did not check if they worked after before deleting the source. Also no backups. Anything important, you keep 2+ copies of.
If the files were encrypted, or saved in some other odd way on the phone, issues could have happened then. There are some utilities that claim they can fix corrupt pictures, but most are junk and pretty much all you need to pay for, but you may want to check around and see if anything looks like it can help with this.
Since files where on the phone, you may have had Google Photos or Google Drive setup to automatically sync files, did you check those accounts to see if the pictures are there? If nothing was setup, then that is something to do for next time.