WD40 will almost certainly not fix the problem with the window. It's one of two things going wrong: either the the window regulator is broken or malfunctioning, or the door window motor itself is not working because it needs to be replaced or isn't working with the electrical system.
Either way, you can probably save yourself some time and frustration by getting assistance from a shop. Door panels are tricky to remove, and the power window apparatus is less than straightforward to work with. If it's an electrical problem, it'll need to be diagnosed.