I have a Dell Inspiron 3521 laptop, Core i3 with 4GB RAM, and a 500 GB hard drive.
I tried to install Ubuntu 13.04 from a USB, alongside Windows 7. Everything went fine and it said restart now to finish. I restarted the laptop and only Windows shows up,and more than 100 GB of the HDD is gone. Please can someone help me get Ubuntu booting?