Keychain login cannot be found

My partners business macbook suddenly signed out of everything last night. We get a [Keychain "login" cannot be found] prompt, we are promted to either cancel or reset all defaults.

All our saved passwords were lost and the chrome browser even reverted back to an old log in i havnt used in 5 years about 4 computers ago which i was very suprised to see.

I reluctantly reset all defaults and entered a new password but the prompt comes right back up in an endless loop.

This is a huge pain in the *** and we are pretty ****** off for this to happen out of the blue when we are so busy, i havn't been able to find anything relevent through searching...

does anyone know what has happened here and how we can fix it?