Mower used without air filter- is it ruined?

So my buddy has a troy built pushmower that he said I can have if I can fix it..

He said it has been having problems starting, and only running for about 10 seconds when it will crank.

Turns out, he took out the dirty air filter several months ago and never replaced it. So my question is fairly simple, is it a lost cause or could i repair?


Thanks so much