Change air filter alittle oil dust make stopup air filter dust being all find particle from moving pollen. The air engine does get run out engine stop running. Air filters should be changed every oil change if oil black its time. simi clean air filter give me problems all time no large stuff just particle can't see.

It depends which way you tilted the mower to clean it. If the air filter was downward, it's not contaminated. Try starting without the cleaner. If it runs, change the filter.

The drive belt is off the pulley, the cable is broken, or the belt is worn out or the adjustment isn't correct.

Better to repost your question using a new subject line.

starts n runs for 5 seconds i have cleand the carb what do i do

Here is a link that might be useful: ask.com

I had this exact same problem after the gas tank ran dry, and I cleaned the carburetor as follows:

1. Turn off engine key and disconnect spark plug.
2. Pump out gas tank (or tilt mower) to gas can.
3. Remove air filter cover (1-bolt, 5/16" socket) and air filter.
4. Remove 3 air filter housing bolts (5/16" socket).
5. Remove air filter housing from hose in back.
6. Carefully remove carburetor gasket from carburetor.
7. Slide fuel line hose clamp 1" up hose (pliers, channel locks) but do not remove hose at this time.
8. Remove two carburetor bolts (3/8" socket).
9. Rotate carburetor CCW to remove throttle cable.

10. Raise the carburetor, remove fuel line from the carb and hook fuel line around the engine key (to keep residual gas from draining).
11. Empty gas from carburetor bowl through inlet into gas can.
12. Blow dirt off of the carburetor with compressed air if you have it.
13. Thoroughly clean the outside of the carburetor with Gumout Carb + Choke Cleaner or equivalent spray cleaner.
14. Remove the bowl nut (1/2" socket) and remove bowl.
15. Thoroughly clean bowl (there will probably be some grit on the bottom) and set it aside.
16. Insert tube in cleaner nozzle and thoroughly spray the aspiration tube and fuel inlet pipe.
17. Blow the carburetor including the two tubes with compressed air if you have it.
18. With the carburetor upright, blow into the fuel line connection. Air should blow freely.
19. Invert the carburetor and blow again. There should be no air flow as the float needle valve should close.
20. Apply anti-cease to the five carburetor bolts.
21. Reinstall carburetor gasket onto the air filter housing.
22. Reassembly is the reverse of these steps. Since this is a single speed carburetor, there are no adjustments.

This worked for me. Replacement carburetor can be found at:
http://www.amazon.com/Briggs-Stratton-498170-Carburetor/dp/B00176FTW0

Oops, my mower was a 2004 Troy-Bilt 22" FWD 6.75hp, not a 21" push, so check your parts manual for the correct carburetor replacement. The cleaning procedure is probably the same, however.

I picked up a Briggs & Stratton in-line fuel filter #298090S at Home Depot. I ran the engine dry and placed a large clean butter tub under the fuel hose. Using a razor knife, I cut the fuel line 3" away from the fuel tank and allowed the gas to drain into the tub. I was surprised that even though the gas tank appeared to be empty, the tub almost filled with gas.

Once the gas tank was drained, I placed hose clamps on each of the hoses, installed the filter then tightened the clamps. I then poured the gas from the tub back into the gas tank decanting away the solids that were in the fuel line just waiting to plug up the carburetor aspirator orifice.

Gas cap had busted rubber inner air valve which was sealing the tank from air. Mower would run for about 1 minute then sputter to stop. Ripped out the piece of carp and replaced with ring of solder wire with gap at ends. Now air gets in, gas gets out, mower runs. Cost of repair nothing but time.