by uninstalling Thunderbird: error message: can't delete because of empty registry

hi,
i have a portable Thunderbird on a USB stick in an encrypted (with TrueCrypt) area.
by removing the stick without demounting it first i damaged my Thunderbird application to the extent that all folders and all mails were gone and i was prompted to set up a new account before being able to use the program.

i wanted to deinstall TB and then reinstall it again. however, by deleting the folders most were gone, except for the Data/Profile/Mail/Local Folders/Inbox and when i try to delete these, i get the error message: Folder can't be deleted because registry is empty.

what can i do now to get red of the remainings of my poor TB?

Thank you for your help in advance
evelyn