hi able to find a workaround on this problem:
here's what i had done:
First-> Backup Server using the Windows Backup (included in Win2k8) -> http://technet.microsoft.com/en-us/library/cc770266(WS.10).aspx
Then:
1. Move the files to the newly created partition which i shrink from d drive
2. Delete D partition
3. Then go to command prompt. Use diskpart:
At Diskpart: execute list volume, select volume 1 (which was the c partition), then execute "Extend"
After executing "extend" c partition was extended to the unpartitioned space
4. But upon restarting the server, it wasn't unable to boot it shows "Boot Mgr is Missing"
5. So I did a "System Recovery" using the backup.
6. After doing the recovery server was up, but some applications need to do reconfiguration.
But it's better than starting from scratch which need to do DC configuration, DNS settings, etc...