Why my pc screen won’t turn on?

@sanchosauce since your image shows on an external monitor (your TV) the issue is within your display. It is either your LCD display that has failed, or the circuitry that drives your LCD. First check for a backlight failure.

A simple check for that would be to darken the room and turn the computer on. Then use a flashlight and angle the light at the screen on different areas. you might make out some shadows or see your actual desktop etc. If you do, it is your backlight that has failed. You would need to take some measurements on the display adapter to see which part of the circuit has failed. Could be as simple as a blown fuse to as complex as a failed LED driver.

If you do not see anything then the issue is most likely the LCD screen itself. You need to consider replacing it. Frr that use the HP ProBook 640 G2 Notebook PC Maintenance And Service Guide PAge 82 will tell you how to replace it.

While you work on your laptop, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!