Sure seems like a hardware issue with that external drive.
Are your backups also on that external drive, or on some other drive?
You might want to try downloading and installing and running a program called an "undelete utility" which might (or might not) be able to recover some of your catalog files. If you are going to do this, do not perform any other tasks with this external drive except run the "undelete utility" on this external drive, and download and install this program to a different drive (not the external drive).
Thanks, I have done something like this before but only been able to recover files names .chk which I haven't really been able to do anything with....is that all I would get from this as well? And do you think this could be related to using Windows 7 & 10 with the same external or is that not an issue? These catalog backups were on the same external drive. I had them there so I could access them from either computer (then I backup online with crash plan). But now these backups I made yesterday were 'gone' before they could ever back up online. I'm going to start saving backups to computer hard drive as well as portable.
There's really no way I can tell if Windows itself is a problem, but it sure sounds to me like the disk is having some hardware problems.
It's never a good idea to put backups on the same drive as the original. In fact, stronger words apply ... NEVER put backups on the same drive as the original.