Hello,
You can try doing a repair on the database by going to "extensions > manage > database" and then click fix in the top left corner. I could take a look for you first hand and see if there is anything I can do to assist. I would just need you to PM me FTP and Joomla login details.
Regarding specific work you've done on the template, if you mean edits to the template CSS or index.php file then yes you can easily back this up. If you mean modules created, articles created, etc then this wouldn't really be possible without a lot of work.
Thanks for that - I have tried the 'fix' but no joy. How do I pm you - sorry if this sounds really stupid but I looked at your profile and there was no obvious way to do it.
Really appreciate your help.