What can I do if I was in a hit and run auto accident, I had insurance but now they said they cancelled it and now I'm being sued?

I was in a hit and run auto accident. I had insurance but now they said they cancelled it and now I'm being sued? I was just served for the suit. I'm disabled and my only assets are my small 401k that is tied up in community property from my divorce. How can an insurance company say I was cancelled and now I'm getting sued? I'm disabled broke and lost.