Front camera or earpiece don't work

First off, that's a pretty heavy mod for a non-professional. You should be impressed with yourself despite the camera/earspeaker problem! I think what most likely happened is that the flex cable that holds those two and the proximity sensor probably got knicked. Just in case though, remove the screen again (ALWAYS disconnect the battery from the board before touching anything else), and take a look at the FPC connector on the motherboard where that flex cable plugs in under a microscope. It's the bottom one of the three horizontals. Confirm that all the pins are present and straight. Before you reconnect the screen, make sure all the connectors are flat on the end of the flexes. They have a tendency to bow and lose connection. If you have more questions just respond, I'll be glad to help