Do you believe in ghosts and why?

I believe in ghost because there is no reason not to believe.

Well, I believe in ghosts because:

One night I woke up and I heard like music, or I don't know muffled sounds I guess. Then (even with my eyes closed) there was this flashing. So I opened my eyes and... nothing, no flashing, no music. I closed my eyes again and tried to go back to sleep. Then I heard the sound again and more flashing, almost like something was trying to get my attention, so I opened my eyes again and nothing! I thought I was going crazy. So I tried to fall back to sleep for the third time and then the next thing I knew, I was hit in the head. It hurt for a second then it left like it never had happened. I looked around the room and no-one was there. It was the scariest thing that has ever happened to me. I think it was a ghost.