Windows XP VPN were missing

All of the XP's VPN connections were missing. Options 'Dial Up' and 'VPN' in the connection wizard were disabled. So, I couldn't make a new VPN connection.

It turn out that I accidentally disable some of the services.
These are the necessary services:

• Telephony
• Remote Access Connection Manager
• Remote Access Auto Connection Manager

After enabling those services, the previous connections are appeared.

http://www.computing.net/answers/networking/new-network-connection-disabled/36178.html
http://support.microsoft.com/default.aspx?scid=kb;en-us;330163