My husband has a Sony A65, a mirrorless DSLR. The viewfinder suddenly quit working today. We can use the LCD screen. The camera is probably 4-5 years old. Anyone have anything like that happen? There is a button that will transfer the desired view from the viewfinder to the screen, but that isn't the issue.
Is there a button to turn off the viewfinder? One of my cameras had a button. Also, some have settings under menu. Not sure if that's it, but worth a look.
may be totally unrelated but, I have a Sony A7 and the LCD screen quit working but I could still use the viewfinder (reverse of your issue). I put a new battery in and problem solved...so maybe low battery?
@amyk sorry to hear about your a7! I changed the battery, but no go. :-(