Maintenance for the week of October 12:
• PC/Mac: NA and EU megaservers for maintenance – October 12, 6:00AM EDT (10:00 UTC) – 8:00AM EDT (12:00 UTC)
• Xbox One: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
• PlayStation®4: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
It's a bug, I've had it appear then disappear. You're still in the guilds you aforementioned, even if it does not show any when you open the guild tab. Give it time before everything settles and it will be working again.
There is an issue with guild and friends lists on the European megaserver that we are currently investigating. For the sake of keeping messaging about it in one place, we're closing this thread and ask that you please head over to this one: http://forums.elderscrollsonline.com/discussion/72062/lost-all-friends-guild/p1