Grub is the GRand Unified Bootloader that comes as the default boot loader in most modern linux ditributions including all flavors of Ubuntu. In easy words it is the software that shows you the operating systems you have installed on your computer and allows you to choose one when you start your computer.
Many new users of Ubuntu often come across situations where they need to re-install boot loader. It happens particularly when you attempt to install or re-install Microsoft windows on a computer that already has Ubuntu installed. Windows wipes out Grub boot record, making user unable to boot other operating systems at start up. But don’t worry there are many ways to solve this problem easily. Visit the Ubuntu Community Docs “Recovering Ubuntu after installing Windows” help page for all these solutions. You will also find many threads about this on Ubuntu Forums.
Right now, I would like to talk about the solution that I found easiest and I think that most new Ubuntu users would also find this solution easier and helpful. This solution also applies to any Linux distribution using Grub.
UNetbootin is the software that allows you to fix your Grub Boot Loader from with in Windows. It allows you to use Super Grub Disk with out floppy, usb, or CD.
- Download UNetbootin for Windows(download .exe file) and install it. Once the installation is finished you will be asked to reboot your computer. On rebooting you see a menu similar to Grub that asks you whether you would like to boot Windows or UNetbootin Supergrubdisk. Select Unetbootin SuperGrubDisk.
- Now you will be presented with a menu where you will find following two options among others:
Super Grub disk (With Help)
Super Grub disk (No Help)
Select Super Grub Disk with help because as the developers of the project say that Super Grub Disk is also an educational tool that teaches you a little about how boot loaders work. It will not take more than five minutes to read help text. Scroll or skip the help text by pressing enter key until you are presented with another menu to choose Language. We see help text again and then we are presented with the menu.
- Select Gnu/Linux from the menu. You are then asked what you want to do.
Fix the boot of Gnu/Linux (Grub)
Boot Gnu/Linux directly
Select fix the boot of Gnu/Linux (Grub). It then presents you with a list of Gnu/Linux installed on your system and you have to choose a /boot/grub/stage1 file. You will see Ubuntu listed, select it and press enter. Super Grub Disk will now try to fix your boot loader and at the end you see “SGD has succeeded”. You are done now, press any key and then select the option to reboot your computer.
- You will see Grub at the start up, select Windows as we need to perform one last action. Once logged in you will be asked if you would like to remove UNetbootin and all its components. Select Yes and UNetbootin will be uninstalled.
Even if somehow Super Grub Disk fails to restore your Grub, you can still boot into your Ubuntu by selecting “Boot GNU/Linux or Boot GNU/Linux directly” options mentioned in step 3. You can then attempt to fix Grub from with in Ubuntu.