On a riding lawn mower, you normally either pull on a knob to engage the blades or you pull or push a lever to get them to operate.
Let’s start with the knob type first. It is a PTO switch and its function is to engage the lawn mower blades and then disengage them. It is wired into several safety switches to prevent it from operating unless the conditions of those switches is met. You can test the switch in most cases by sitting in the seat, turning the key to the on position and pulling up on the knob. you should hear a metallic clicking sound indicating the PTO clutch is working. Check the belt as well to be sure it is in working order.
If you do not hear this, one of the safety switches could be bad or the associated wiring, a blown fuse or the PTO switch or PTO clutch is bad.
If you have a lever type blade engagement, make sure that it is not binding, the cable is not broken or the belt is not off the pulley or broken.
Those are pretty common problems with lawn mower blades not working. If you need a lawn mower repair professional in your area, visit our locations page.