Can't connect to my instance anymore

My instance https://us-west-1.console.aws.amazon.com/ec2/v2/home?region=us-west-1#InstanceDetails:instanceId=i-c6edef82 is not accessible using ssh anymore (was fine before). Restart doesn't help.
I assigned the role https://console.aws.amazon.com/iam/home?region=us-east-1#/roles/MySessionManagerInstanceProfile to it, but still can't connect using session manager. Can't use the serial console because I don't have a user with password.
Please help.