BuddyPress.org

Ok, guys, this is very easy to fix, IF you have a backup of your DB tables.

Open the backup .sql file and do a search for wp_bp_user_blogs (substitute wp_ for whatever your DB prefix is). Find the line that starts with:
INSERT INTO `wp_bp_user_blogs`

Copy that line, open phpMyAdmin and paste the code into the SQL tab. Hit enter and the blogs reappear.

If you don’t have a DB backup, then you have to manually enter all your blogs into that DB table. Or write a little script that does it for you.

Hope this helps you guys!