Problem with the pen tool

Hello, I have come to my wits end trying to figure out a solution to my problem. I want to draw a straight line with the pen tool. Whenever I draw my line and I click on a different layer, the line disappears. I can't change the color of the line, it's the same color of blue as the anchor points, which leads me to believe that something in the settings is leading to my demise. The line is on top of all the other layers, so that cannot be the issue. My pen tool can create a line, but it can't create a line that exists! The line keeps disappearing and isn't editable, so can someone please help me out? I'm begging you.