When you recover local folders, just copy the mbox files; the index msf files will be recreated when TB restarts. Delete the msf files, with TB closed, and see if the folders appear after restart.

Thanks sfhowes but I did delete the .msf files to have Thunderbird recreate them (should have mentioned that previously). The folders were recreated but were still empty. My assumption from your response is that there should be some content in the folders if I did copy the mbox files over from the crashed computer to the new computer. Still, no content in the folders.

In normal cases, what you did should work, but if the crash affected the integrity of the mbox files, they may not be readable by TB. I would see if one of the 3rd-party mbox to eml converters can read these mbox files. Eml files can be imported to TB by drag and drop from an Explorer or equivalent folder to a subfolder of Local Folders in the TB interface.

Thanks sfhowes, based on your first response, I decided to look into one of my operational folders on my own Thunderbird with a text editor to see what I should expect to see which appears to be the source code for emails. When I try to do the same thing on my friend's file, it is full of gibberish (and not the good kind). Looks like these files were trashed. So, even though it appeared as if I got the files from the crashed SSD, in fact, those files were trashed. So "no mas", as a famous boxer once said, I am throwing in the towel and letting my friend know that these files are not salvageable. Thanks for your help.