Access Denied errors

Setup a new SP2010 environment and created several site collections. Everything was configured and worked fine. The users I gave permissions to could log in successfully.

Noticed that the service accounts were not correct (ie. app pool services not using my AppPool active directory accounts).  Modified the farm admin account to the appropriate AD account, also the various apppool services.

After doing so, no one can view the site collections. Not even my account, which is a site and farm administrator. Rolled back the changes to the service accounts and rebooted the server.  However, it still displays "Access Denied" on all site collections.

Help! I really don't want to start over.