To see what is the format of the tabulation of your HardDrive, go to My Computer, select a Hard Drive then click on Properties.
If your hard drive is not formatted as NTFS, you have the possibility of converting it without loss of data and special software. Attention!, conversion is irreversible with the Microsoft tools. If you have several operating systems on your computer, it will not see any more the data of partitions NTFS and perhaps, programs won't start any more.
1. As a safety measure, you might want to make a complete backup on a CD or DVD. A problem might occur, even if it's usually rare.
2. Click on the Start Menu and select RUN. Type in:
cmd in the dialog box.
3. In the Command Prompt Window, type in:
Convert L: /FS:NTFS (L: is the letter of the drive)
4. If some files are currently in use, the command prompt will probably propose you to force a temporary unmount. If you're trying to convert your main drive with Windows installed on it, you will have to reboot your computer. In that case, the conversion will occur when rebooting.