Ubuntu doesn't boot after installation [duplicate]

Since you mentioned you have used three partition I will assume you want a dual boot not an wubi install.

Boot using a live usb/cd of ubuntu. Use boot-repair to fix the problem.

After booting with live usb/cd ,Run following command in terminal,

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Use Recomended Repair

At the end it will give a link , note it down before rebooting. If the above doesn't work just post that url here.

More information can be found here- > https://help.ubuntu.com/community/Boot-Repair

Assuming you installed your Ubuntu system alongside Windows (by booting from a CD/DVD or USB flash drive and running the installer), and not inside Windows (with the Wubi installer), this problem can almost always be solved easily by reinstalling GRUB2 to the Master Boot Record, using any of these methods.