Unfortunately for you this OS is designed to keep you out if you do not have the password. If you have previously backed up the software and data then you may need to do a resistall, restoring the data after the restore. If this is the sole server yeah you are out of luck. If there are other servers and you work with others I would think all of them have the same administrative password and someone can give it to you. I am sure there are utilities out there which hackers have published to get you in, but I would not begin to tell you what they are nor would I publish them here if I did know them.
Re-install the operating system and keep the file system intact. It will reset your registry values, but some applications will still run. This is only for a quick fix so you can backup the files before a full reinstall by formatting the disk.
There are some other way to reset Windows password with a bootable CD/DVD or USB flash drive. 1. Reset windows password with Ophcrack 2. Reset windows password with “Advanced WIndows password recovery tool” These tools is to reset the password offline.