Hmm. Let's talk this out. Is it a push or self propelled mower? Did the tangled wire stop the blade from turning, or did it just make a bad noise? Did you turn the motor off when you heard it hit the wire, or did the tangled wire cause the motor to stop on it's own?

I assume you checked to make sure there was still gas in it, and that the spark plug wire is still connected. If it is battery powered, has the battery discharged.

In my experience, that is just about all that could go wrong that I can think of.

Good luck.