• I tried pasting in the history.mab and abook.mab and restarting Thunderbird but none of the contacts appeared.

Did you mean you pasted in history-1.mab and abook1.mab? The only mab files that are automatically recognized are abook.mab and history.mab. To import the others, close TB and rename abook.mab to abook.bak. Copy abook1.mab into the profile folder and rename it to abook.mab. Start TB and see that Personal Address Book now contains the abook1 contacts. Create a new address book, name it abook1, close it, then select all the contacts in Personal Address Book (Ctrl+A) and drop them onto the abook1 icon. Close TB and delete abook.mab, then rename abook.bak to abook.mab. Restart TB and you will see the original Personal Address Book as well as abook1. A similar method works to import history-1.mab.

Thank-you for the quick response.

I did do as you said, renaming the files and re-starting TB. That much I'd picked up from searching the web. Personal Address Book does not contain any addresses, so I am stuck with what to try next.

I don't need to have multiple address books, just wondered if that was a different way of retrieving the info I've lost.

The multiple address books are just a way to temporarily store the imported contacts during the renaming process. 'Personal Address Book' is empty - is that the original one when you set up the new computer? You can move contacts from the 'imported' address book, abook1, to PAB by drag and drop, then delete abook1 if it's no longer needed.