Lawn Mower won't start?

It is possible that when the string got caught up in the blades that it stopped the engine and sheared the flywheel key. If the key is sheared or even damaged it will effect the ignition timing and the engine won't start. You will have to remove the engine cowling and the flywheel nut to inspect the key. To replace the key you will have to remove the flywheel. The best way to remove the flywheel is with a puller. The flywheel nut is torqued to around 50 ft/lb, that is important when putting it back together. Remove the spark plug wire before any work for safety.

Sounds like to me that you have a flywheel issue, you need to take it apart to check. Make sure that you pay close attention to detail when taking apart to ensure everything goes back together smoothly. Also the issue could be a clogged fuel system and need to take off the cover and clean out the house and housing between the gas tank and engine.

check fuel and oil level, then press that little button u do when you go to cold start, and if it has a lever you can depress to give power to the wheels press that down when you go to start, if that dont work maybe try the carbirator. I found with weedwackers on a cold start i bump the button 10 times, hold the throttle and put it on choke then pull 2 times and it will catch then just flick off choke and ur in buisness, that should work for you

When you turned the blade did the engine turn too?

I had one that did not turn the engine. No flywheel effect for the engine to start...

a new plug will probly fix it