Hi Titelbech,
Try going into plugins folder and temporarily deleting the plugins. When you visit they should then get deactivated and this will rule out any plugins being the issue. You can always upload the plugins again after you get things working and they'll stay deactivated, then you can activate one by one until you break - although activating will trigger the plugin to "set itself up" again so it might actually not break anymore. No data will be lost this way if you remove the plugin folders - since you're not deleting from within WordPress database settings and storage are safe. And you have the plugin data files in your backup too.
Also, make sure the URL for your website is the same as it was during backup. Changing the URL will certainly break things (the backup is for recovery, not for migration.) If you did change URL you will need to do some things in the database to fix URLs etc. More information on that in WordPress Codex at http://codex.wordpress.org/Moving_WordPress
You can also search "Moving WordPress'.
Regards,
Jason