re :messages stored on old harddrive which have been imported on to my current pc

What exactly did you import and where did you import them into? You would need to import mbox files (they do not have an extension) as mbox files contain emails. See image below showing an example of mbox files.

You would have needed to import them into 'Local Folders' mail account.

Please explain exactly what you did. Did you manually copy and paste the mbox files into 'Local Folders' in your profile folders whilst Thunderbird was closed? Did you use an addon tool like 'ImportExportTools' to import the mbox file into 'Local Folders' mail account?

Thanks Toad Hall

So I followed the instructions i found on a mozilla support page titled 'Restoring to a different location'. With thunderbird turned of I copied and pasted the contents of the old profile folder into the new folder thunderbird created when installed on to the new machine. I did not use an add on tool.

Yes I believe i have those mbox files. they appear inside the sbd files and are just called inbox.. without a file type listed.

I had deleated the .msf files in an attempt to allow thunderbird to correct its directory.

Appreciate your kind help with this.

So basically: Installed thunderbird and it created a new default profile name folder typicalled called 'xxxxxxxx.default' where the x's are letters and numbers. Then you copied all the files and folders in the old 'profile name' folder. Accessed the new default profile name folder - removed default contents and pasted in all the copied contents of the old profile name which included an old gmail account that no longer exists.

It seems the old gmail account was an imap mail account that maybe connecting to an empty server hence all folders would show as empty or your Anti-Virus has disliked those mbox files and deleted them. Only the index files still contain information but they point to nothing.

Try this: Exit Thunderbird.

Access the new 'profile name' folder. Click on 'Mail' Click on 'Local Folders'

Access your backed up copy of old 'profile name' folder that has the old gmail mail account folders - they are probably in the 'ImapMail' folder. Copy only the mbox files (no extension) and paste them into: new profile name\Mail\'Local Folders' folder. You can organise them later.

Start Thunderbird. Folders should appear under 'Local Folders'.