Your old insurance company dropped you after your accident, right? If so, it is the still the one on the hook for paying out for your car accident. You make your accident claim with the company under which you had coverage at the time of the accident.
Your new car insurance company will take care of any claims for incidents that occur after the inception date of that policy; it will not cover past accidents or damages.
If your old insurance company dropped you before your accident and you obtained coverage with a new company after the accident, then you had a gap in coverage and have no insurance provider to file claims with. This is a bad place to be since you would have to pay personally for any damages, to your car or others, if you were at fault in the incident.