DNS problem after switching to AWS domain registrar

I transferred my domain name to AWS registrar one day ago. I already had my website hosted with S3 since last year. Ever since I transferred, website is inaccessible. I would think AWS would repopulate the Route 53 nameservers or is this even necessary? I am not a techie in this area, if someone could please explain what I need to update. I'm at a loss as to why the change in domain name registrar to same place I'm hosting, would cause this. Thanks!