Assuming you're intending on installing an OS (otherwise there wouldn't be a concern on how it is presently performing), just put the OS disk in your CD drive and boot off it. Follow the steps and it will format the drive for you.

If the installation disk doesn't pick the drive up, open the side of the case and make sure it's connected properly. There should be a Molex connecter from the PSU connected to the back of the drive as well as a data cable (either an ATA ribbon cable or SATA cable) that is running from the HDD to the motherboard. Then make sure the drive is actually enabled in the BIOS.