A little more information would certainly assist us in helping. What kind of computer are we talking about?
Are you referring to a flashdrive?
Are you trying to format it?
1. Type devicemgmt.msc in Vista Start menu or in Run dialog box.
2. Expand Disk drives, right click on your USB stick which you want to format in NTFS
file system and select Properties.
3. Under the Polices tab, select Optimize for performance option. Click OK and go back to My Computer.
4. Right click on your USB drive; select Format.
5. Select NTFS (yes, it's available now) from the drop down menu.
6. Click Apply to format your drive in NTFS file format.
7. You are done.