Answer to: Cracked/ unresponsive screen but screen still shows up and powers onIt's probably the digitizer but the LCD is glued to it, so you would just buy the whole piece together. You wouldn't be able to connect the digitizer to your current LCD, so yeah, just buy the whole thing on Amazon or Ebay. Hope that helped!
Answer to: Display works but touchscreen broken LG G2Hi! I have the same problem with mine right now. I've been looking around online and it seems like the LCD and digitizer are glued together so you'd want to buy them together. I typically buy phone parts from Amazon because it seems to be the most reliable with the most reasonable prices, but you could get them anywhere, really. I wouldn't suggest getting something cheap, but there's no need to get an expensive name-brand. If your phone is under warranty fixing it yourself will probably break it, so just make sure you're prepared for that. I hope that helped :)