A couple of weeks ago I dropped my Nexus 4 and cracked the screen. The touchscreen was still working ok, but I went ahead and replaced the screen anyway. Here’s how…
On the Nexus 4 the screen is bonded to the touchscreen digitiser behind it, so unless you want some major hassle it’s easiest to just replace the screen and digitiser as one unit. You can pick up kits on Ebay to do this, mine cost about £45 and included screen, digitiser, tools and the frame (which was nice, as my screen frame was getting a bit worn).
I followed this video. The only things I would point out are that it’s easier to remove the SIM card holder first. Doing this makes it easier to pry the back shell off. If you’re replacing the whole screen unit you also don’t need to worry about heat the screen and seperating the components. Don’t forget to transfer over all the fiddly bits like volume buttons and the headphone jack from the old frame to the new one.
It’s not at all hard to do, with the right tools it’s just a matter of working carefully and methodically. My phone is good as new.