Clonemonkey

Hi All, I have just started using Prestashop for one of my clients and have run into quite a few issues. Firstly I needed to upgrade to 1.6 in order to get a payment module to work. The upgrade was successful eventually after several timeouts, but all of my images disappeared which I have later found out happens (not good). So I decided to roll back to 1.5, but now have the issues that the rollback had errors and I'm not sure it completed properly and I now can't access the site at all from the back end as the admin no longer exists. There is 1 errorThis account does not exist. Please help. Thanks