Steam deleted all my games on my external drive

[thwackmorg]

I store a bulk of my games on an external USB drive, about 700 gigs worth, and suddenly I started getting missing executable errors from them. I checked the steamapps>common folder on my library, and everything was missing. The weird part is steam doesn't seem to realize it, and it thinks that the files are still all there. the same goes for the drive itself, since it still thinks it has all the space from the games taken up, so I think they might be hiding somewhere?
Does anyone have any experience with this kind of problem, and know a way it can either be resolved or prevented in the future? I'd also like to know how to get that wasted space off of my drive, if I can. For clarification I'm running Windows 10 and the drive is a Seagate Backup Plus Ultra Touch.
I already tried resetting, unplugging and replugging, and repairing the library, and nothing seems to have changed. This is a big pain in the ass and frankly pretty frightening, I'm worried about this happening to my C drive too. It also may have coincided with some GPU trouble, where I did a clean reset and install of the drivers, but I don't know how those could be related.

[Mad Scientist]

External media must be connected BEFORE launching Steam to have games be recognized

[Iceira]

Just add steam multi lib again, well it work on my DAS usb, cant say it will on yours, but why not.

[Joke]

Use the windows check disk utility on the USB drive.

Right click the drive -> Properties -> Tools -> click the first button (labeled "check" or similar)

[thwackmorg]

That was scary, but I managed to figure it out! I used the command menu to recover the files, I think there was some kind of hardware error. the commands I used were "chkdsk F: /f" followed by "ATTRIB -H -R -S /S /D F:*.*", which scanned the drive for any bad stuff as well as dropping what it could recover into some other files. After a bit of searching I found what was recovered from my common folder, and was able to just cut and paste it back where it belongs. So far everything is still fine, but I verified the game files just in case. I found the instructions for this on this webpage [www.cleverfiles.com] so shoutout to the lady who wrote it, I guess. Hope this helps anyone who stumbles upon this problem in the future.

[Lithurge]

If there was a hardware error then you should replace the drive or at least make regular backups of the content as it's likely to get worse until it fails altogether.

[Valeriya]

Surely you have made some mess, Steam does not delete the games from the peripherals, it was enough to format the hdd and reinstall by recreating the steamapp folder.