Locked computer

Hi,

When I logon, i then have to keep logging on if I stop typing for a bit or change screens. I am using widows 8. I went to the bottom left and cl start then went to upper right corner where my picture is cl that , I cl on the word lock...did this a few times to see if this would unlock. This may not be the place to do this. It was working just fine and now it is not. Seems I must have cl on something by mistake.

Thanks for helping