If I let my cousin borrow my car and he wrecked it but I didn’t know that my insurance was canceled, what steps should I take in this matter?

Unfortunately, in a situation where you do not have auto insurance coverage, you do not have many options.  I am not sure how you were unaware that your insurance was cancelled, but in most states there is not a requirement that insurance companies notify you of cancellation of your auto insurance.  Some companies will notify you, however others will simply cancel the policy, usually for lack of payment.  If you feel your policy was cancelled in error and you really should have had coverage at the time of the accident, you can try to resolve this with the insurance company.  Whether or not you can resolve it depends in large part on the reason for the cancellation.  Ultimately, if your policy was cancelled for legitimate reasons and you did not have coverage at the time of the accident, you are on your own with respect to the damage to your vehicle and the costs of repairing or replacing your car.  Technically, your cousin can be held legally liable for the cost of the damage.  You have to decide for yourself whether or not you want to go after a family member for this.  If your cousin is unwilling or unable to cover the costs of this, you would be forced to pursue it through formal litigation and again, you must decide if you wish to sue a family member for this.