[ubuntu] Unable to booting into Ubuntu

I have Ubuntu 15.10 alongside a Windows 10 OS. My issues has nothing to do with the latter btw (I hope).

I had few tutorial videos in the Videos folder in Ubuntu, which I wanted to move to another folder (which I wanted to be at /, called videotutorials (or whatever)). I successfully created the folder, at /, and performed sudo mv to that folder, and the whole computer froze. I left it there for almost half hour, even then, nothing. Then I performed RIESUB on it, after which, every time the computer was booted, it shows attachment file #1, named 1.jpg.

If I exit it (by tying exit), it exists and shows the second attachment, called 2.jpg

The only way I can enter Windows is by opting the last option. If I hit the fourth, it just goes back to the first screenshot.

Please can you help?