How do I restore an NTFS file system?

Recently we experienced a power outage that resulted in the unexpected shutdown of an NT 4.0 Server. When we rebooted the machine, the hard drive was recognized by Windows but the volume didn’t contain a recognized file system. Is there any way torestore the drive to NTFS without formatting, as we don’t want to lose the data (about 6 GB) on the drive. We were thinking of using a data recovery service, but they can be very expensive. If anyone has any ideas, please respond. Thanks