Would it not engage any gears when the engine wasn't running? My first thought was that the clutch plate has stuck to the flywheel, but if that was the case you should be able to get it in gear without the engine running.
Mine has stuck on a couple of occasions but the important thing then is to run the engine to get everything warm. Sometimes it's enough to leave the clutch depressed overnight and it frees off. Otherwise your stuck with warming it thoroughly and then starting in gear and driving with the clutch depressed until it clears. More drastic is to warm through and then tow the car in gear with the clutch depressed until it frees.
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