The command line in Windows has been around for over 2 decades so my next move would be to copy them with a command line back to where they were.

Remember we only lose what we don't backup so I hope you didn't reduce your photo files to just one copy. That's very unsafe and how folk lose all their files. Especially on externals.

So how about using Irfanview from https://ninite.com/ to try to view them?

Also, how about other file copiers? I use Roadkil's Unstoppable Copier but you may like another at http://lifehacker.com/5280976/five-best-alternative-file-copiers