Yesterday night, I have installed Ubuntu 12.04 LTS through Wubi, since I don't want it to be on a CD or a USB. Later that night, I have updated the version from 12.04 LTS to 13.10. It asked me to reboot to complete the installation of the update, so I did that.
Afterwards, like normal booting, it asked me which OS do I want to open. Windows 7 or Ubuntu, so I chose Ubuntu, of course, but, after I clicked on the Ubuntu button, the Ubuntu start up screen shows (the Ubuntu logo which has five grey loading dots under it) and then it disappears and turns into a black screen with a white line. The white line isn't even moving. What's going on? Please help.