Windows Server 2008 DNS Server Down

On a Windows Server 2008 machine while trying to start the DNS Management window DNSMGMT.MSC fails with the error:

"The server <Server Name> could not be contacted."
“Access is denied. Would you like to add it anyway” (YES | NO)

The problem I am using user Administrator to login and still it gives access denied error.

On firing dnscmd it gives me error

>dnscmd.exe  <Domain Name> /Info

Info query failed
    status = 1722 (0x000006ba)

Command failed:  RPC_S_SERVER_UNAVAILABLE     1722    0x6BA

When I restart DNS Server from Server Manager it gives me below error:

The DNS server was unable to complete directory service enumeration of zone mydomain.com. This DNS server is configured to use information obtained from Active Directory for this zone and is unable to load the zone without it. Check that the Active Directory is functioning properly and repeat enumeration of the zone. The extended error debug information (which may be empty) is "". The event data contains the error. –

In my case, the hosts file at c:\Windows\System32\drivers\etc\hosts had the following two lines hashed out:

127.0.0.1       localhost
::1             localhost

I uncommented it but of no use,

It was running fine till yesterday and suddenly today it went down. What may be the cause?