Briefly I installed windows and then when I tried to install Ubuntu on a separate partition it couldn't see the Windows partition. So I opened Windows but I had lost the use of my mouse and keyboard. So I put in the Windows installation disc and tried to correct the partitions, but I had trouble navigating using only the keyboard. I ended up deleting the wrong thing and then my Windows installation was screwed and I was concerned that the partition table had gotten screwed up too. So I decided to format the whole disk and not knowing much about it I went about it the wrong way. I was going to use data destruction software because I could do it without being in an operating system. However I think I aborted that before it actually did anything as the program hung and afterwards it didn't seem there were any changes. Finally I was advised to use the following command in order to save time formatting an entire disk when it probably wasn't necessary.

dd if=/dev/zero of=/dev/sda bs=1M count=10

Right now the Windows installation disc says it cannot install on this disk, and on the disk utility using the ubuntu live CD, it gives me an error when I try to format the disk - error synchronizing after initial wipe timed out waiting for object.

I'm pretty desperate now. What do I do?

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    Try sudo sgdisk -Z /dev/sda from an Ubuntu live disk. This should wipe all the MBR and GPT data structures. If it fails, or if subsequent steps fail, edit your post and provide the exact and complete error messages. (If they're long, post them to a pastebin site.) – Rod Smith Jan 21 '16 at 23:13
  • @RodSmith I was advised to get Windows to create a new partition on the disk, and that worked. That was shortly before your comment showed up. Ubuntu was able to see that partition and once i'd checked that, i installed it with the 'install loader alongside Windows loader' option and that works fine right now. – kim holder Jan 22 '16 at 1:22
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    To add details: dd to wipe the beginning and the end of the disk. GPT keeps a backup at the end of the disk and I have no idea how windows [installer] acts when it only finds one copy. Also to installl windows on a disk with GPT partitioning you need to boot windows in EFI mode. And to install windows on an old style MBR partitioned disk you need to boot it in legacy CSM mode. Whatever partitioning style you choose will be used for all operating systems. So eiher use MBR and install both Windows and Ubuntu the old way. Or use GPT and install both that way. – Hennes Jan 22 '16 at 8:59
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    The command you quoted wiped from the beginning only. If you also want to wipe the end then we need to seek further into the disk and start writing just before the end. This post on SU describes a nice way to do that: superuser.com/questions/128860/… – Hennes Jan 22 '16 at 15:40
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    The point of sgdisk -Z is that it wipes both the main and backup GPT data structures, at both the start and end of the disk. This is much easier than computing the sectors to be wiped at the end of the disk with dd. – Rod Smith Jan 22 '16 at 21:50

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