Have you checked your Drive account from a PC or Chromebook? Maybe it's just an isolated incident on you Pixel and the files are still stored probably ...
Glad you got it worked out! I know losing years worth of files would have been horrible!!The problem is fixed. I've been trying al morning to find the problem.
To fix it, I uninstalled it. It left me with 2 choices. UPDATE & OPEN. I chose UPDATE. When I reopened Drive, all the files were there. GO FIGURE.