Chosen Solution

if i get a replacement screen will the phone work or is it beyond repair

Your question is a little vague but my understanding is that you replaced a cracked screen and now it doesn’t “light up”. Have you tried putting back the original screen to see if the problem is with the phone or if it follows the screen? If the problem is with the device, shine a bright flashlight on the screen when you connect it to an iTunes enabled computer. If you see a dim image, then your problem is with a blown backlight circuit on the logic board. This would require a micro-soldering repair.