Just entered a write-up in Halls of Wisdom.
It could be the battery. Make sure the battery connections are clean and tight. I've seen perfectly good batteries "die", but it was merely a SMALL amount of corrosion at the terminals. Remove both - and +, wire brush, apply some dielectric (bulb) grease, and put back together VERY SNUG. Put back + first, - last. This helps reduce the chance of swinging wrench hitting the chassis somewhere, and sparks flying, and toasting something.
If everything is clean & tight, try CAREFULLY jump starting it with booster cables from another battery or car. Just to see if you can get some life from the starter button...
If not, you have other issues.