Thank you very much rafaelluik and LeoCG for the very swift response.
I guess I should have really filled in more information before I hastly posted my topic. Yes the browser is set to "Continue where I left off", and I am aware of the session .db file which I had backed up to another drive, however when I open Opera I still return to only 1 Tab and this may be due to Opera auto-updating.
The Session.db file is 192kb in size so either this is good or bad but I have no idea what the nominal size should be. Personally I had about 40 Tabs Open and these were for cross comparison between projects eg: Scientific calculators and theory etc. I really appreciate the replies thus far
and had read all the About stuff that you suggest rafaelluik so thank you for clarifying that but the Session.db.bak is also 192kb in size so fear the backup of session.db is probably the same as the original, however with try as you suggest my good friend and hopefully get back some of my Tabs.
Since then I have also installed a program to manage sessions (odd how I never done it earlier as I has Session buddy on Chrome, and session manager on Waterfox).
Thanks again guys and I can hopefully get back to work.
All the very best Spencerino