Sounds like the excentric weight (which is responsible for winding the watch) has either stuck or the ratchet has failed.
I suggest you have it examined by an Omega service agent. If you go to http://www.omegawatches.com/customer-service you will be able to find your nearest dealer or service agent.
different watches have different case backs. You need to send a picture with yours or send the model number so we can see what is the case back system. Omega has many vintage ladies models.