see attached image

Is there an Old Firefox Data folder on the desktop with a replica of that folder? If so, check whether it seems to have the missing contents, since we then could use it for recovery.

If no Old Firefox Data folder:

Have you already shut down and restarted Windows to try to release any locks on the folder?

If you right-click the inaccessible folder, Properties, Security tab, is there anything strange about the permissions that might prevent you from opening the folder? You can compare to the other folder.

i shut down and restarted and the old profile folder disappeared. i found another profile on a second computer and installed that one using profile manager. only half my bookmarks and passwordds missing...better than nothing. question is, where did the old profile disappear to?

PFCM said

where did the old profile disappear to?

Did it more to an Old Firefox Data folder on the desktop by any chance?

If not, you might try something like the following to undelete it, to the extent possible: https://www.piriform.com/recuva

You can do a disk check with the chkdsk.exe program. If you run the chkdsk.exe program from a cmd.exe Command window then you can read the response from the chkdsk.exe program. Open a cmd.exe window: Start > Run: cmd.exe <press Enter> At the command prompt (>) type or Copy&Paste: chkdsk.exe /f /r <press Enter> (put a space before /f and /r) If you get something like: Would you like to schedule this volume to be checked the next time the system restarts? y/n then answer the question with "Y" and close all programs and reboot the computer.

You can also try to take ownership if the folder via the right-click context menu.