BuddyPress.org

I had been running WordPress 3.1 multi site and BuddyPress 1.8. The network consists of only two sites, one WP site and another running BuddyPress. Everything, as far as i am aware, was functioning properly. I upgraded to WP3.2 and BP1.9. Both updates were implemented via the auto update function. Now the WP site is running fine but BP will only load the static pages, the main menu links: activity, members, groups, forums and blogs all result in a 404 page not found message. I am using the BP columns theme, which I thought may have been causing the problem, so I tried the 1.29 BP default theme and disabled the other plugins but it made no difference, I re-saved the permalink structure, which is the numeric option, but that did not make a difference either. Unfortunately I did not back up (I do have a back up from a few months back). I would dearly like to get the site running again and seeing as i have not seen any similar posting on these forums am wondering what has gone wrong. I do not have a deep understanding as to how all this stuff works so i am at at a loss as to what to do. Can any one suggest the things I should now be checking. I have made a similar post to this in the Installing BuddyPress Group but so far no one has been able to help.