Hi ! I don't know if I am right here but I would try to ask how to test if my lcd 20x4 is fine or my friends has broke it. Which wires I have to connect to test it ?

Hi and welcome,

please read the instructions "how to use this forum". Your information is way too less to give you a sound advice.

  1. Please post a link to the datasheet of your display.
  2. What sketch do you use (use code tags, when posting your test sketch -> what that is: read the forum guidelines/instructions (a link is in my signature below)
  3. Post a picture of the solder spots of the display and the connections between display and Arduino