Easier to fix your config than re-create it, if you still have the config there and the folder formats are just pointing to the wrong drive letter.
- Fully exit Opus (via File / Exit Directory Opus).
- Open
C:\Users\<username>\AppData\Roaming\GPSoftware\Directory Opus\Formats\folders.off
in your favorite text editor. - Save a backup somewhere.
- Do a search & replace of
A:\
toB:\
(or whatever the letters are).