'Automatic' update gone wrong!?

Hi there!
I've been using TBP for some time now and have had no issues so far.

However, whilst checking emails it 'announced' that a newer version was available, would I like to update? I clicked yes.

It displayed that it was downloading the update, came to the end and explained that Thunderbird would have to restart to complete the update.

So I let it restart, but after ten minutes it still had not restarted. It had closed TBP and seemed to have stopped all activity. There was no activity on the laptop at all!

I gave it another ten minutes but still no restart. In the end I left my laptop on all night and went to bed. In the morning, TBP had still not started again, so I attempted (after checking still nothing was active on the laptop) to restart TBP manually i.e. double clicking on the ThunderbirdPortable.exe on the flash drive.

Now, however, it just gives a pop up saying:
"Mozilla Thunderbird, Portable Edition cannot be started. You may wish to re-install to fix this issue. (ERROR: thunderbird.exe could not be found)"

I'm a bit concerned that re-installing it will loose all my emails plus my contacts and as I can't even open TBP to back them up I'm not sure what to do.

When TBP announced an update it did not give a version number and unfortunately I do not recall the version I was using except that I would surmise it was the latest version as I have done this previously a short while ago.

So is it possible to backup emails and contact lists from 'outside' Thunderbird (copy and paste a file or two thru windows explorer)?

Or could a 'simple' re-install not delete the email folders and contacts, so would be the thing to do? I have downloaded the latest version of TBP from this site so as to be ready to re-install if needed.

Many regards!