Sorry, we're all on holidays at the moment. We will be back in the office next week.
I'm not an expert on the way the whole leveling system works, but what you described sounds very strange - I will have to get Steve to look at.
Just to clarify, you are saying that you were level 50, with a full team of survivors and a pretty much fully complete compound - but somehow your account was reset back to level 12, and the number of survivors you had reverted back to 5, and you lost a bunch of your buildings?
If you could answer the following questions, I'm sure it would help sort out the issue.
How long ago did this happen exactly?
Do you remember any crashes, bugs, etc.? or did you just log in and it had happened?
Do the survivors that remain still have the same names?
You said that your neighborhood got reset - is that true? Do you remember anyone in particular that was in it?
I noticed you are in an alliance - and that you joined it recently - were you in one previously? If so, which one?
Do you have any weapons above level 12 - if you were at a higher level then your inventory would contain items from those levels. If not, did all your inventory disappear as well?
If you could get back to this, it will help whoever looks at this next week.