Can I file a claim if the damage happened over a month ago?

My kid's dad fell asleep while driving my car and hit a guard rail. He is not injured or anyone else, but the accident happened a month ago. Can I still file a claim with my insurance company?

As long as you have collision coverage on your policy then the fact that it's been more than a month should not matter. I would recommend contacting your insurance company's claims department to start the process.