Local Folders folder won't expand

Somehow my local folders have collapsed, and I can't reexpand them. Some I can see in explorer, but some are invisible. I use the portable version. thanks.parmil
Posted previously in Tbird support forum. Question unanswered.
10/11/15 12:59 PM
When I tried to create a new folder with explorer in the default "local folders" folder on my hard drive, I am told there is already a folder with that name. That's what I mean by invisible.

Further info: I will try the PortableApps forum. It didn't occur to me the portable and installed versions would be that different. Is the PortableApps version different from a portable version? If so, how did you know which one I was using?

Looking deeper with explorer, I see 5 of the folders in the default location (Data/Mail/LocalFolders) with .sbd extensions- they are visible and I am able to move emails to them. Don't know if I can retrieve them. They contain what I thought I created as subfolders, but they are extensionless files with data, together with same name .msf files.

Beneath them (in the explorer view of the local folders folder) are 8 (0 kb) folders or subfolders I had created, with same name .msf files that have from 2(mostly) to 219 kb data in them. A couple of these are the same name as the empty 2 visable folders with .msf extensions. One of these is the last folder I created in Thunderbird (before, I think, the local folders folder started to refuse to expand), the other is the "new folder" I created in the "local folders" folder with explorer(to see what would happen in tbird). I tried to name that one of the extensionless files, but explorer wouldn't allow me, giving the error message "file already exists".

Sorry I don't have time to make screen shots (as this must be hard to visualize) right now, but will, if someone suggests this. I'll try getting my hands on a universal viewer program to see if the data is emails. I think there are, but I don't know what program I need to open .msf and .sbd files.