Windows Server 2008 Administrator Password Reset

Question

Hi friends,

Our Windows Server 2008 Administrator password has been changed automatically. I have mentioned the server configuration details below. Can anyone help me how to reset the Administrator password without formatting it.  Thanks in advance.

Server Configuration

OS - Windows Server 2008 Standard

Manufacturer - IBM

Model  - IBM System x3400 M3 Server

Processor - Intel(R) Xeon(R) CPU E5507 @ 2.27 GHz 2.26 GHz

Memory - 24 GB RAM

System Type - 64 - bit OS

Regards,

Arunkumar.T.V