I do not see anything right off that would cause an issue necessarily. It might be lines 24 and 25, clamping the position, but I'm not positive.
I would try adding print statements to your code to make sure all the parts are working. I would start with checking to make sure your inputs are being processed correctly, then checking that the variables are correctly set when moving, and finally checking the values being added to the position. Its a bit tedious, but that should help narrow down why the player is not moving.