Hello,
I bought a Fairphone 4 last year and installed the eos operating system by myself. Everything worked fine - until today. When I switched on, the mobile phone suddenly reappeared in initial mode, i.e. in eos mode, but without any apps and data that I had later. There was no announcement, no update, no signal that anything was changing.
What happened and how do I get my data back?
Stephanie
Welcome to the Community Forum.
This vaguely sounds like Safe Mode. The Support article concerns Fairphone OS only and I do not know how it is triggered in /e/OS. Maybe someone else here knows.
You might also want to try to find out at https://community.e.foundation
UPDATE: Done here 
Eos ungewollt zurückgesetzt - Fairphone - /e/OS community
Tried rebooting the phone?
Sounds to me a little bit like you accidentally executed the factory reset which might happen when you (for what ever reason) end up in the recovery mode, i.e. by pressing certain buttons. I think it was ‘power on’ and ‘volume down’ at the same time… or by locking the bootloader.
I’m using eOS for several years on several (Fairphone) phones. So far eOS never factory reseted by itself…
It’s possible that this has happened, I’ve already thought about it. But is there a way to undo it?
Yes, but nothing changes…