You probably damaged your mother board. There is a little chip above Audio jack flex connector check if it still there if it is missing that is the reason for front camera not working.
You can create a little jumper to fix the problem. See this pic
Hope that helps.
Hallo i tried this yesterday to make a jumper between this two points and after that my front camera worked perfect but it stopped to make calls the carrier was gone and when i was trying to make a call to somebody his phone was ringing but my phone it was dead i didnt hear anything. After that i removed the bridge to see if this was the problem but the problem was still there and the front camera stopped again to work. After few hours the problem with calls stopped without to do something. Do you have hear this before? It happend beacause the jumper or is something else that just happend?