Do I need a screen, digitizer, LCD or all 3?

[iMore Question]

My phone touch screen has become quite unresponsive after being dropped, particularly on the left hand side, it also thinks that it's being tapped in certain places when it isn't. The glass is totally fine, and so is the image on the screen. I'd like to have a go at repairing it myself, but want to save money and not buy unnecessary parts.

 

[kch50428]

Some parts places have all 3 parts as one assembly priced cheaper than the parts separately...