Blade will not engage

Last weekend I was mowing my lawn and noticed that after I turned my blades off and set the brake to move my trampoline. After moving the trampoline I got back on to mow the underneath part and noticed that the blades would not engage. The blade does spin freely when it is not engaged so I know it’s not seized. I am new to working on this mower so I do not know what drives the blade to know where to start trying to fix it.

post complete Snapper model & serial numbers, there should be plate or sticker on mower, check your belts

good deal!

Never mind, false alarm. The belt had just come off the tensioner. I adjusted the tensioner and put the belt back where it goes. All good now.