Yes we know you did not delete 400 posts obviously not , i just said you deleted just 1 post of your own from yesterday by yourself : )
but it really has to be down to Forum Upgrade/Rebooting , i can recall this happening just once before but it really is rare it may have happened more than one time in the past but i do not recall any member loosing so many posts .
it is not a good situation but admins will work very hard to discovery why so many of your posts are gone this matter will not be taken lightly at all and none of us want to see this happening please remain patient for further updates from Forum admins ,
Thnx