[Windows Central Question]

I have had nothing but problems with my emails since downloading Windows 10. I have already recommended my acquaintances DO NOT DOWNLOAD WINDOWS 10.
I have lost all my email history and when I click on a folder I get a message telling me it is "not synced yet". Finally it tells me, "We didn't find anything to show here."
A couple of days ago I could find them on my old (but friendly) Acer where as this Toshiba is an awful computer.
Now when I go back to my Acer I am being asked to log in with an 8 digit code (2 x 4) but each time I enter tha correct code it simple throws up another 8 digit code and so it goes on.
Is this 8 digit code a scam? How do I recover my email history (easily) please? I am not a computer expert just a simple sole trying to make the most of technology.
Sarah