Raffky,
1. Check for spark (should be blue).
2. How old is fuel?
3. Check carby 'O' rings don't have any damage.
4. Try removing exhaust (muffler) and see if it starts.
5. Check fuel for water.
Try this stuff and let us know but we do require more information as to what happened when the mower stopped.
Also do you have the blade plate on the engine?