my insurance company is saying i had a lapse in coverage and refuses to pay a claim hoever i have proof in writting.

If there is a question of a lapse or gap in your insurance policy, the letter that you received from the insurance company that indicates you had insurance at the time of the accident does seem to be credible evidence of insurance.However, if there is other evidence from the insurance company that indicates that they sent a notice of cancellation for non-payment of the premium, the letter will indicate the date the insurance was set to cancel. If that date is before the accident, and you did not pay the premium on time, then the insurance company could deny coverage, even though they sent the letter saying there was coverage on the car.If you have proof that you paid the premium on time and so the insurance policy would have been reinstated, then that along with the letter saying you had no lapse in insurance should be sufficient to serve as proof of insurance at the time of the accident.