I am a novice with Linux, so I'll offer suggestions that use the file manager. - locate the profile on olddisk. POP messages will be in the Mail\<POPaccount> folder. look for files such as input, sent, trash. Ignore the msf files. the addressbook will be in the root folder of the profile. look for two files: abook.sqlite and history.sqlite - be sure that thunderbird is not running - copy the above mentioned files and paste the addressbook files into the profile's root folder, overwriting the initial ones there, and place the message files into the Mail\Local Folders folder. That will allow you to view messages although they will be separate from their respective accounts. - restart thunderbird and all should be there

All files and directories under ~./thunderbird

Are you asking a question? Please clarify

Its a long story, but i "fixed" it by using the old version of thunderbird. Ubuntu switched from apt to snap versions of thunderbird with 24.04, and they handle files in completely different locations.

Best solution i found was to purge the snap version and load an apt version via a ppa.