Mowing the Lawn????????????

Ok, so when I was mowing the lawn I went over a couple sticks and rocks...and it kept going....and then I didnt see a tree root..and I went over and it just stopped...and then I proceeded to mow the rest of the lawn and it worked fine..the whole time...I sharpened the blade a month back and its fine...then 2 days later started it and the front wheels..that are self moving would turn..and smoke and a smell of burning rubber went in the air....and then when I stopped it it wouldn't start....is it because of the sticks and stump that the wheels aren't turning..or something else? Toro Lawn Mower.