8/2/2012--- update, do not try the method shown on youtube, where it asks to put your iphone in the oven, my iphone bricked.
other than that, only software to help to atleast get the 3g back is the post below.
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EASY SOLUTION!!!!! SO TYPE IN WHITED00R in google, and you'll FIND OUT MORE ABOUT IT, DOWNLOAD IT FOR YOUR IPHONE 3G ON THE IPAD BASBAND, IF IT'S NOT GETTING 3G or its NOT GETTING SIGNAL AT ALL. WHITEDOOR: is pretty much a custom firmware for iPhone 3G and older devices that simulates the 5.0 software, although your iPhone will be running on 3.1.3, it will have all th latest features, and it'll be fast. And of course, YOUR CONNECTION WILL POP BACK UP NOW IF YOUR WIFI IS NOT WORKING, THEN YOU NEED TO REFLOW THE PCB(YouTube it) THANKS AND GOD BLESS