A driver was being chased by police and ran into me, my car is totaled. I called the insurance company They said I was covered. But now say I'm not.

You need to see an attorney to investigate whether the denial of coverage by your insurance company was legitimate or not. You don't say why they cancelled the policy. Was it for non-payment? Why did they return the down payment. Since you say your coverage was cancelled on the day of the accident, you can't pursue a claim through uninsured motorists' coverage although you may sue through the NJ Uninsured Motorists' Fund. If you look to sue the driver of the other car, ask yourself whether you think a person who drives uninsured is going to have money to pay a judgment? Lastly, if the police were engaged in a legitimate and not grossly negligent pursuit of the other vehicle, you will have great difficulty proving a claim against them. You also have only 90 days to file a notice of claim against the relevant police dept. (and town, county or state agency it belongs to) in order to preserve a right to sue.