You could boot using a Live Linux disc to fix it. Once booted you could use GParted if you like GUI's or
fdisk through the CL.
- GParted is pretty straight forward
- Open GParted as root
- Make sure you are on the correct device (top right corner has a dropdown list)
- Select "Partition" and "New Partition Table"
- The default is MSDOS, but you can verify this via opening the advanced arrow.
- Apply the change
- Then you can right click the (unallocated space) line and Add New > fat32/ntfs/etc. You could also skip this step since it has a partition table, and finish in Windows.
fdisk is more in-depth as it is command line base.
- be sudo first in the terminal (
$ sudo -i)
fdisk -l to list your discs, verify which one is yours (you will want to know the line that says
/dev/sdX (X is just a placeholder for a letter) (the windows one will probably have sdX1 sdX2 and so-forth)
- Double check that you KNOW which hard drive you are messing with
- Now that you know, type
- You can type
o to write a new MSDOS partition table.
- 'n' will make a new partition, choose 'p' and '1' and then accept the defaults for the next two (first and last sectors).
- Select 't' for type, and '1' for NTFS (just to get you back to Windows to finish again)
- 'w' to write the changes to the disc (if you feel you messed up, 'q' is quit and won't write changes)
- Now you need to make the NTFS formatting on the drive, so install
sudo apt-get install ntfs-3g
mkfs.nfts /dev/sdX1 (If you followed above, you made 1 partition on your disc, so you want to write that to that partition not the whole device).
Important: I am assuming that you did the whole external device and that you want to fully wipe the thing. If that is not the case, then let me know and we can work on that. However, this will wipe the drive of your data. So measure twice, cut once (i.e. double check everything and understand it before blindly typing the above).