Nikon d40 PC connection lock?

One day when I turn on my Nikon d40 its in "PC connection" mode…
I often connect it with my laptop, for my Ebay products. It also works well
when its connected to the computer but when you detached, PC connection mode again.
What should I do?

Added (1). When you turn it on,
its say "PC connection" I dunno why, also all buttons won't function.

I can't tell what you're asking… Please explain your question.