Quartz watches that have been in drawers for a long time are usually in poor condition. They get put away when they stop running and over the years the battery ends up leaking and causing damage to the movement. Judging from the staining on the dial its likely that's happened in this case.
there will be a case reference number in the back, that will allow you to trace when the model was current. My guess is late 70s/early 80s, Omega made lots of different variants.
Depending on the movement it could be expensive to get fixed, parts for the early quartz stuff are v. scarce. Unfortunately the cost of sorting it out is likely to far exceed its value, I would send it to STS as they're folks likely to have access to parts. It'll not be cheap, possibly that won't worry you?