Re: i cant access my blogg after installing buddypress :(
It looks like you also have the 3rd-party plugin bp-registration-options installed and activated. If you can log the dashboard as Site Admin, then go to the Plugins menu and deactivate the plugin bp-registration-options. If you cannot login to your site, then manually remove the bp-registration-options plugin from the /plugins/ directory.
Either way, that should bring your site back up. You will then need to contact the plugin author and tell him/her about the error.
NOTE: This thread should be moved to the support forum Third Party Components & Plugins