Dell Inspiron 570 - power save mode/amber light

Hello, I don't know allot about computers, but each time i turn on the computer it goes to power save mode.

It asks me to press any buttons or click the mouse, i do but nothing happens, neither the mouse or keyboard light up as they use to, only for a slight second once its turned on, then it goes away. The little bulb on the back of the tower is steady green and i use a vga cable. I'd like to know how to fix this problem so I could use the computer.