I am new linux.

someone changed my login username and password.I couldnot login into machine now.i have windows xp on my HD.

MY question is can I delete this partition from windows(disk management).Should I reinstall xp so that the other partition is visible to it.

Could you clarify a little more what you currently have?

You had Fedora ONLY installed before and now installed Windows, or had Windows installed previously and then Fedora (dual boot senario?

Do you have the grub splash screen still, or the Windows bootloader only?

Windows XP disk management should see your Fedora partition as "unknown partition."

You can't uninstall Linux from Windows per sae, just delete the partition. This does not get rid of Grub from thew MBR.

But I wonder what you mean that someone changed your login and password? Others may have had access to your system without your knowledge, or you are using a computer that is used by others as well.