Several people are complaining on EA's Battlefield: Bad Company forums that all their stats and weapon unlocks have been deleted.
However the plucky Eurogamer forumites have found a solution:
You simply use this link - http://badcompany.ea.com/myprofile/xbox/****/ - replacing the '****' with your Gamertag or if you're a PS3 owner, replace the words 'xbox' with 'ps3' and the '****' with your PSN ID and your stats should magically reappear.
No official word from EA at this point.
By Mike Bowden