How can I restore my "Unknown" partition type, back to NTFS?

Lately I've been having trouble restoring my PC after uninstalling GRUB, and an Ubuntu install from it. Usually I don't encounter any problems when doing this, but this time is different. My Windows XP (NTFS) partition is listed as "Other" in Partition Magic, and "Unknown" in GParted rather than "NTFS".

How can I gain access to Windows partition once again? I am more than willing to provide any information, and run any tests necessary to produce said information in order to find out what's going on here. My apologies if this is the wrong place to ask such a question. I have heard nothing but good about Superuser, and decided to give it a shot. Thanks!

4 Answers

sfdisk should be able to "fix" this problem easily; something like this should "work":

sfdisk /dev/sda -i -c 1 07

However, it's possible that in addition to the partition type being changed, the partition positions (start, end) were also corrupted. TestDisk should detect these issues and write a new, somewhat proper partition table.

The thing is that considering the partition table was corrupted, it's possible, no, likely that the data is too.

From what I understand, it seems as if your MBR (master boot record) was either overwritten or corrupted. Have you tried restoring it from within Linux? You can do so with the ms-sys tool by running this command:

ms-sys -m /dev/sda

The -m switch is for Windows 2000/XP/2003 so make sure you use that switch if you have Windows XP.

To repair your BOOTMBR (building off last answer because I can't comment yet):

1. Put the Windows Vista or Windows 7 installation disc in the disc drive, and then start the computer.
2. Press a key when you are prompted.
3. Select a language, a time, a currency, a keyboard or an input method, and then click Next.
4. Click Repair your computer.
5. Click the operating system that you want to repair, and then click Next.
6. In the System Recovery Options dialog box, click Command Prompt.
7. Type "Bootrec.exe /FixMbr", and then press ENTER.

I've done this several times after having problems with Grub and linux installation.

You can also recover your disk with the "chkdsk" command.

1. Boot computer with a Windows XP disc.

2. Go to recovery console

3. Type the command like

   C:\> chkdsk /r 

4. Wait until process is complete. Restart and see.