Hey everyone. Sorry for the rough stretch today. I just got Quizlet back up after some pretty heinous downtime. Everything should be 100% back to normal, and none of your data should be lost. Feel free to moan in the comments.
UPDATE: Some users have reported finding their groups deleted. I've tracked this problem down to some code on the groups page that will delete a group when there are no members in the group. When the Quizlet database was up-and-down today, sometimes the users table was not working but the groups were. So groups that were visited when the users temporarily disappeared may have gotten deleted. Fortunately I have a back-up from early this morning with all of the groups. It looks like about 15 groups may have been deleted. I'm going to work on getting those back up as soon as possible. Sorry for the trouble.
UPDATE 2: Restoring the data from today's early-morning backup went very smoothly. All deleted groups should be back up. Post in the comments if you're still out. Sorry again.