I don't think this is specific to Thunderbird but more a general issue of your desktop environment. There may be a configuration setting to show hidden folders. And there is probably some way to enter the exact path to the .thunderbird folder in the import dialog.

Hey Christ1, Thanks for your reply. Every other file selector dialog on this box has hidden files showing. For TB's there is no path box or any other options. I thought it strange but I don't think I missed anything. I had to move the profile to a non-hidden folder to get it to load. That did not solve the issue, I think the folder is too small to be the lost profile as nothing came back with it. Somehow my GRUB bootloader got borked and (initRAMfs) did a repair that wiped out all of TB & only some settings in Firefox & disabled all it's extensions. The drive booted right after that but was Read Only. A second reboot returned Write privileges, but only Mozilla stuff was messed up as far as I can tell. More research is in ordrer I guess, before I resort to a TimeShift restore.

  Thanks for trying to help.

re : hidden files and folders.

does this link help: http://kb.mozillazine.org/Show_hidden_files_and_folders#Linux