This is the common problem which is faced, when you try for dual boot. Recently I have posted the article on How to Recover / Re-Install Grub in Ubuntu using Boot-Repair from live cd / usb. Boot Repair is the simple graphical tool used to repair, restore or reinstall the grub bootloader on Ubuntu. Now this tools has been updated with some new features in advanced option, using boot- repair you can also restore the MBR on Windows.
On dual boot once you update your Ubuntu OS, your Windows / Fedora will not be listed on your grub. After installing Windows / Fedora your Ubuntu will not boot anymore and its grub may be wiped out. To restore it follow the steps below
To Reinstall Grub
You need to have Ubuntu Live CD or Live USB. Normal session can be used to repair the grub. Boot using your Ubuntu Live CD or Live USB, while booting choose Try Ubuntu.
Once booted then open a terminal, and run the following command one by one to install the boot repair.
To add boot-repair to the repository
sudo add-apt-repository ppa:yannubuntu/boot-repair
To Update your repository
sudo apt-get update
To install boot-repair
sudo apt-get install -y boot-repair
Once Installation complete run boot-repair on terminal by typing the following command or select it by System->Aministration->Boot Repair.
NOTE: Update the Boot Repair if its newer version is available.
It will scan the System for few seconds and will show you the options Recommended repair and Create a BootInfo summary. By clicking the Recommended Repair it will start repair the grub. Check the screen shots below.
Once done click ok and restart your system, your grub should work now. If not run the boot-repair again using live cd / usb. Then follow the steps below.
Select the Advanced options, In Main options tab check whether the following options are selected or not. If not select it, the options are Reinstall Grub and unhide boot menu for 10 seconds. Check the screen shot below
Then select the GRUB locations tab and check the following options are selected or not. The options are OS to boot by default and place grub into, In “OS to boot by default” option choose the OS which you want to be default on boot. Then select the drive where you need to reinstall the grub in “place grub into” option and click apply. Check the screen shots below
Click ok and restart your System. To restore MBR Click Here.
Hope this will be helpful for you!!!