Search your drive for a .tsbak file. It will be called something like uninstall-8.0.tsbak. Use this to restore your server.
If you need help, please contact our support team here: Upgrade Assistance | Tableau Software
Create a backup and save it in a temp directory or some where away from any Tableau directories. Uninstall Tableau Server. Delete every single directory that is Tableau -- for you that would be both directories (and their sub-directories) you have mentioned. Now you can install 8.1.1 64-bit (yes, they have a new (patched) version). Once installed you can then restore your backup.
This is what I had to do and it fixed everything for me. If you're still having issues then do as Dan says and contact support.