restore Magento Database and Finish Upgrade

I have made an upgrade of my store to magento 1.4.2. Unfortunaley, it did not work correctly ( the home page was showing a 404 with the default template) so I tried to restore my shop to the previous version : No way to restore the database completely. I need the database to be restored (if possible, with version 1.4.2) and my store to run correctly. I can provide 1.4.1 database and 1.4.2 database, and files for both versions. Here is the url : [login to view URL], you can see there is no product and the template is not showing. Thanks for helping