After moving Thunderbird folder i.e. ~/.thunderbird to another computer, it could not find the mailbox of the profile. It created a new profile. This was due to the change in the path where ~/.thunderbird folder was restored.
To overcome this issue, open a terminal window and enter the following:
$ cd ~/thunderbird <enter>
$ ./thunderbird -profilemanager <enter>
and select the profile to open. This will then open the mailbox.
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