How do i fix a computer when its safe mode?

How do I fix a computer when its safe mode?
Yesterday I used my computer and shut it down after. Now, I open my computer and I was shocked because my computer is in safe mode already. But my friend told me to press F8 and choose from the options that will I appear. I did it but nothing happen. I didn't do anything from the last time I used it. I even shut it down properly. I restart it when I saw but when it opened I still the same again.
I don't know what to do anymore. Can someone knows this kind of problem? How do I fix it?
