Error after changed instance type at AWS portal

I changed instance type at AWS protal from micro to small. It seems have cuased problems:

1. I can not access my wordpress website from bitnamiapp.com subdomain
2. When I try to re-start the instance from bitnami, the instance at AWS can be stopped, but not restarting the instance, I guess the linking between bitnami and AWS is broken?
3. My website's pages are not loading properly. I guess it's because my style sheet files's path are missed

So how I can restore the connection between bitnami and AWS after I changed the instance type?