Deleted all the GPT Partitions by accident

Hello, I recently purchased Dell XPS 8700 that came with a 2tb harddive formatted with GPT. The computer came with Windows 8, and I wanted to downgrade to Windows 7. However the windows installer wouldn't install on any of the current partitions, so I deleted every partition with gParted and proceeded to install Windows 7 successfully onto the one giant partition. Since I deleted all the GPT partition information (Idiotically), I am unable to make more partitions and dual boot.

So my questions are: Is my harddrive as of right now in MBR or GPT? And how would I add the GPT partitions back, as in the primary and secondary GPT headers?

Edit: I am attempting to dual boot with Xubuntu 14.04 and Windows 7 Professional, both 64bit and the computer has the UEFI, I think. Am I better off using MBR or GPT to dual boot? I only want two OS's and a shared data partition.

Since I deleted all the GPT partition information (Idiotically), I am unable to make more partitions and dual boot.

Deleting all GPT partitions is a recommended step to downgrade "Windows 8" as "Windows 7" is known to not much liking GPT based UEFI boot mode. Although "Win 7" 64 bit edition may boot from a GPT disk, i prefer MBR partitioning especially in case of dual booting with Linux.The only mistake you made here is not to partition the disk at the time of install. Fortunately you can split the single large "C" partition to two or three small partitions with the help of "Partition Wizard" free edition.


Download link : Best Free Partition Manager Freeware and free partition magic for Windows 7, Windows 8, Windows Vista and Windows XP 32 bit & 64 bit. MiniTool Free Partition Manager Software Home Edition.


What you need to do is first shrink/resize "C" and create one or more new partitions using the free space.


How to shrink partition : Shrink Windows partition with partition manager - MiniTool Partition Wizard.

Video guide : How to Move/Resize Partition with partition manager? Partition Wizard Move/Resize Partition Video Help.

Okay awesome :) I just have one more question though. When I try to resize with a program like gParted, it tells me that harddrive still has the GPT signatures but doesn't contain the fake msdos as it should. I do i need to take an extra step to convert my hardrive entirely to MBR? Because right now, I'm not sure if it's MBR or GPT.

Thank you for your timely reply. I just have one concern, when I use a partition program, like gParted, it will tell me it hard drive still has GPT signatures but doesn't have the fake msdos to go with it. gParted then says my whole drive is empty. Is this because I haven't converted to MBR? And am I still able to do so now that I deleted all the GPT partitions?

If so I found these instructions:

1. Boot into the Ubuntu Live CD. Alternatively, get the latest version of Parted Magic or System Rescue CD, boot it, and skip the next two steps.
2. Go to the GPT fdisk (gdisk) download page and obtain the latest version (0.6.13) for your architecture. I'm afraid I missed what that was, if it was stated. It'll be either the gdisk*i386.deb or gdisk*amd64.deb file.
3. Install the gdisk package file. Double-clicking on the desktop should do this, or you can type "sudo dpkg -i gdisk*deb" in the appropriate directory.
4. Open a shell and type "sudo sgdisk --zap /dev/sda". It'll complain about partition problems, but it will still work. Be sure to use the --zap option, not --zap-all; also, note that the command name is sgdisk, not gdisk.
5. Proceed with your Ubuntu installation.

Is this what I need to do?

The gdisk manual states that the zap function should do the follow:

"Zap (destroy) the GPT data structures and then exit. Use this option if you want to repartition a GPT disk using fdisk or some other GPT-unaware program. This option destroys only the GPT data structures; it leaves the MBR intact. This makes it useful for wiping out GPT data structures after a disk has been repartitioned for MBR using a GPT-unaware utility; however, there's a risk that it will damage boot loaders or even the start of the first or end of the last MBR partition. If you use it on a valid GPT disk, the MBR will be left with an inappropriate EFI GPT (0xEE) partition definition, which you can delete using another utility. "

EDIT: Sorry for double post, I thought the first one didn't go through