If you have installed more than one Operating System in your PC. For example, you have Windows 7 & Ubuntu installed and suddenly you are unable to boot to any of the OS. If the error similar to given below appears:
A very simple solution for this would be to boot into the live CD/USB and run Boot Repair
Boot Repair PPA
Boot into Live CD/USB.
Type the following in terminal(one line at a time)
sudo add-apt-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install -y boot-repair
Run Boot Repair
Type in terminal
Click the Recommended repair button
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After the process is finished close everything.
This should solve your problem.
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