All custom assets and vmfs gone after PC Reset?

You'd need to reinstall everything unless you backed your things up anywhere. If you want VMFs back, you could perhaps decompile released versions of the maps (if there are any) and fix everything that decompiling broke

Resetting your PC means wiping your files, so they're gone. If you haven't made significant storage changes to your newly reset PC, there are programs that can detect and recover files that have been even permanently deleted, but these are not guaranteed to find what you're looking for. Aside from that, your best bet is to just manually redownload everything that you can. If you didn't have your VMFs backed up elsewhere (you really should start doing that, if you haven't), then in that case, your best bet is decompiling the compiled versions that you've posted to the internet.