I have a mcufriend.com 3.5" LCD screen which works fine on my old Pi but shows just a white screen when connected to a pi2. Is there any way to get this screen working on the Pi2?
If you're talking about this screen I'm afraid there is no drivers available for it. I've asked a similar question on the RaspberryPi.org forum a while ago but the question was left unanswered though.
I've also tried to rewire, but no avail. I'm afraid your LCD will have to stay married to your old Pi.