I disabled the administrator account and now i can only log on as a local user. I tried to re-enable the administrator, but access was denied. I also tried to turn off the UAC for the local user account or run as a administrator, but it didn't prompt for password and access was denied. Is there any other way to enable the administrator account?

You problem is not enough clear. If your administrator account is a local one and you have disabled it, you should have another administrator account which allowed to you to perform a such thing. So, use it and re-enable it. If your administrator account is a domain one and you want to re-enable it, use another administrator account to re-enable it on active directory. If this does not help, use a backup or restore point to restore your system state using a restore point or a backup that dates before the appearance of your problem. This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. Microsoft Student Partner Microsoft Certified Professional Microsoft Certified Systems Administrator: Security Microsoft Certified Systems Engineer: Security Microsoft Certified Technology Specialist: Windows Server 2008 Active Directory, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Network Infrastructure, Configuration