How to Recover Your Windows Bootloader in Ten to Fifeteen Easy Steps
Wow, bud, you messed up. Good news, though, there's an easy fix after which you can start laughing at yourself. I can already laugh because I've done worse. So, welcome to the club. 8D
I've had to do most of this very recently. It seems like a lot of steps at first, but you probably know most of this already. Don't panic, none of it is hard, and there're loads of resources online.
What you need to do:
- Repair windows' boot loader. This should get you into windows, even if it can't see your ubuntu partition.
- Do all the backing up you should have in the first place and recreate your recovery media (if you can).
- Boot into your Ubuntu Live CD/USB. Repair its bootloader (grub2) and run a customizer tool to properly detect and include Windows in its bootloader.
This will work most of the time. If ubuntu's installation or boot-recovery still can't detect your windows partition, you won't be able to dual boot without making some changes. Decide which OS you want for now and work on those changes when you're comfortable.
What you'll need to do it:
- A windows 8/8.1 installation media. (See below) Put this on a disc or usb.
- Free software to create your windows 8/8.1 installation media. (See below)
- A product key. You won't be installing Windows, so you might not even need this to use the recovery tools. If you don't have yours handy (and it's hard to find with OEM installations), you can use a "generic" key. I won't post it here but google will find it for you. It's perfectly legit; you can't activate an installation using a "generic" key.
- A Ubuntu Live USB, on it you'll want:
- Boot-Repair comes standard on Ubuntu's live media. It's pretty easy to use comes standard on it, but if not it's easy to install.
- Grub Customizer will help you scan for Windows and edit your grub2 bootloader. I prefer terminal commands, but this gui tool is great.
Getting a Windows 8/8.1 Installation Media
This is the only hard part. Microsoft used to make ISO files for their installation media available, but they no longer do for 8/8.1. If you know anyone who has one, or even has an OEM recover disc for a different computer, borrow it. They should both boot into its recovery mode. Otherwise, you're stuck looking for an ISO in all the usual ways. I found this article helpful in this regard: How to download and install Windows 8.1 for free
Put the Windows 8/8.1 onto a USB
This should be easy for you, you've already done it for Ubuntu and other distributions as well. The Windows Installer program for Windows 7 works for Windows 8/8.1 as well. Life Hacker has a good article on it.
Boot into the Windows installation media you borrowed or created. Choose the recovery "Advanced Options" until it offers you a command prompt or shell. I'm not sure if you want "bootrec /fixmbr" or "bootrec /fixboot". They both worked for me. How To Fix The Windows Bootloader
Boot Windows - Yay!
Hopefully you have a new boot loader that gets you into windows. Do your backups, see if you can recreate your recovery media, and find your Windows Product Key. Keep it on a piece of paper, OS installers rarely eat paper.
Use Ubuntu to Scan for Windows and Creat a Dual-Boot Bootloader
I was never happy with the way the Windows bootloader handles a linux os, so I stick with Ubuntu's grub2. It is possible with EasyBCD, but I didn't like its results. Log into ubunty, open a terminal and type "boot-repair". More on boot repair.
Add Windows to Grub2
I don't remember if boot-repair will look for your windows installation. Grub Customizer is good at scanning. Its tabs and menus are easy to understand. There's an "Rescan OS" tool that will be helpful.
If all goes well, you've got both of your operating systems on Grub's bootloader, you've configured which one you want as default, and life is good.
Still Can't Find Windows?
If Ubuntu's installation or boot-recovery tools still can't find Windows on your hard dirves, Windows might be using a type of partition table that linux can't see. I don't know enough about it to be explaining anything, but you'll want to convert your partition table to "mbr". (Used to be standard on Windows.) Once you're sure you have a "mbr partiton table", linux and grub should find your windows easily.
I found these two articles helpful:
The Differences Between MBR and GPT
Convert GPT Disk to MBR Disk
Want to Try Windows' Bootloader Instead of Grub?
Like I said, this isn't as hard as it sounds. I gave it a try, but ended up preferring Grub2. Ubuntu Geek has a good article on it.
After this, you'll be a bootloader pro and feel more comfortable screwing up your partitions in the future. Good luck!
New Info - BIOS Settings
Hey, I saw in your comment below that you mentioned EFI firmware configurations. Have you, or are you able to enter your bios settings and disable UEFI and/or Secure Boot? I wasn't able to even boot from a LiveUSB until I did that and enabled Legacy Boot. All this is done in the bios settings. I figured you're past that, 'cause you got Ubuntu installed.
I don't know enough to advise you, and different hardware will have different access to settings. If you think this might be an issue: UEFI - Community Help
Windows Fast Boot
Once you get into Windows, you'll want to find and disable "Fast Boot". Fast boot stores info same as powering-down into hibernation mode. I can't think how Fast Boot would be directly causing your problem, but if nothing else, it's a "best practice" suggestion to help out down the line.
More info on Fast Boot and Dual Booting Ubuntu