ENgine sounds half strengh, (blades turn pretty sure) but don't cut

My mower got stuck on a tree sapling, not the blades- but it somehow got stuck to the front of the engine. I pulled back to free it and all of the sudden my engine sound is half of what it was before. The blades move but don't cut. Can I do something to fix this or would anyone know how much it would cost to repair? I don't have much money and they want quite a bit to look at it alone. There is a little rubber thing on the front, maybe spark plug cap, that may have got tangled in the branch? Thanks



Bolens 21" Push mower

550 series briggs Stratton engine

5.50 Torque