vanished files from bridge

I assume you've used Finder to look for where they may be? If not in the obvious places, have you tried searching for them using the Finder Search function (starting at the top of the hierarchy)? I've dragged files around before and had them not show up, and a search reveals I dropped them in a different folder by mistake. Sometimes even just refreshing the window in Finder will have them show up. Anyway, you probably have searched already using those methods but I thought I'd mention it just in case.

Try time machine to get them back.

I always copy the files from one drive to another and then confirm their existance before deleting the old files.