# Does engine turn at all when you engage the starter?
# Does the starter make any sounds that indicate it is trying to power up?
# Have you attempted to turn the engine over by hand to see if the engine will turn over? If there are mechanical problems with the engine it might be seized or something perhaps.
# To address the only real question you asked, no the electric PTO (blade clutch) on mowers these days have so many interlocks on them these days it is very unlikely that is the problem. Typically riding mowers have a seat switch and a parking brake switch that must both be in correct position to enable the mowing clutch to be energized.