Small Engines (Lawn Mowers, etc.): engine wont start, fly wheel, plastic cap

Question
Hi. My situation is the following:  The plastic cover that sits on top of the flywheel and engine has broken, and therefore, if i go to start my mower by pulling the chord, it won't turn the top of the engine (not sure the name of the part i'm referring to), since the plastic cover that houses the pulley mechnism, won't stay on the mower.  No apparent way to attach it to make it stay since the piece of this cover that was bolted on has broken off.  Any ideas?  Also, the engine stopped working the other day, altogether. Smoke was coming out of it, and it just shut off.  The oil leaked out since the plastic cap became loose.  Thanks for your help/suggestions.

Answer
Hello Eric,
To revive that pulley I would conside getting a new cover or housing. The reason is because the teeth that engage to the fly wheel are not engaging at all. Try to order a new one. As for smoke coming out of the engine is probably because of no lubrication to the piston. What I would like you to do is examine the color of the oil and the oil level it self. Write back to me so I can determine the problem properly. Thank you. Hope this helps.