So today suddenly all but the very latest (added within this week) users disappeared from MySites and our People Directory.
What could of caused this to happen? How can I restore everyone's profiles?
I am using SharePoint 2010.
If you have a backup of the User profile Databases (Profile DB + Social DB) don't need the sync DB. Once you have restored and configured your UPA, and run the user sync jobs (full + incremental) a few times, query the Profile DB database:
Select * from userprofile_full (nolock) where bDeleted = 1
(Not recommended but I had to do this:
update dbo.UserProfile_Full set bDeleted=0 where bDeleted =1)
The next time the User profile sync job runs it will clear the users that do not exist anymore in AD
Refer to this article: http://rehmanfaiz.blogspot.com.au/2014/01/restoring-user-profile-service.html