Are you saying that when the gear selector was moved, it didn't actually go into gear, or was it that the car was in gear but when the clutch was released, nothing happend? It is possible that the clutch facing is stuck to the flywheel and if that's the case, getting the car into gear with the engine running will not be possible. To break it loose, you can either put the car in second gear and on a flat wide open surface, with the pedal depressed, start the car. The motion of the starter lugging against the engine and transmission should be enough to break it loose. If that doesn't work, put the car on a lift and remove the clutch inspection cover. With the pedal depressed, you should be able to use a wedge to pry the clutch from the flywheel.
It's not uncommon for them to stick...mine did in my 50K after only sitting for a few weeks past spring. I was able to bump it loose.