Network choking

I am using AWS EC2 instance in which a website is running. Today i have faced a issue, suddenly my website down, and when i checked, the instance was running and there was no issue, but "i was unable to ssh" and also the ping response was "time out". After 30 minutes everything was normal. I can't what happend. I also checked the instance logs but i didn't find anything. I thought there was a network issue at AWS end. But how i confirm this ?? Also I have a basic support plan, how i contact and report this issue to AWS