1987 Saturn SL1 Engine won't turn over

While driving my car, the oil liht blinked once and then the engine died on me after pulling over I tried to start the car, but only got a click sound, after checking the engine for loose wires I found oil under the car and noticed the oil drain plug had fallen out, the engine was still pretty cool after it died. I bought a new oil plug and replaced it, filled oil level, but still the engine won't turn over. Is there a safety reset that keeps the engine from turning over, or does it sound like the engine seased up. The engine didn't make any noises what-so-ever when it died, and the oil light did not give but a seconds notice. Would appreciate your reply, Thanks jefcher