is that the JD 145 lawn tractor ?
I have a JD160, and when that happens - as it does occasionally, I check that all of the mower belts are still in working order (mine has 3 belts). other possibility is that the blades are obstructed ... grass, dirt, plastic bag (or in my case last week - a large carpet fragment that was buried in long grass). immediately shut the machine off, clear any obstructions on the blades, check that the belts are all present and accounted for... then try engaging the mower again. maybe that will solve it. in the meantime, briefly running the engine shouldn't hurt, but don't engage the mower.
fuse under the toggle switch ?