Can someone give me code for random.range in the y axis?

Hi, So I've asked this question a number of times, and no one seems to know. It's driving me completely mental!!!! I have an enemy that starts on the right of the screen and moves to the left. When it reaches the far left, it loops around, but it loops in the same place as height goes. Every time it loops, I want it to randomly go to "this y position"..... but no higher or lower that "this y position" if you understand. People have been telling me to stop asking questions and just comment on other questions I've had, but there's no one there to comment with. Could someone please help me? Thanks in advance ;)