iPhone 3G - Uninstall the jailbreak from within the phone When I used to connect my iPhone 3G with the computer (via a non-original USB cable), it used to work and iTunes could read the phone. I decided to revamp the phone and jailbreak it since it was on stock OS (iOS 4.2.1), so I send it to someone to do the work.

The phone came with Cydia installed (with a couple of games), however, since then, my computer cannot read the iPhone at all, even as a hardwared connected to the USB port.

My guess is that the jailbroken iOS caused the problem. So, by uninstalling the jailbreak, I may get it to connect. Currently, the phone is completely paralyzed even with a Wi-Fi network and Cydia. I have tried (after some research) operating on the phone on both Recovery and DFU mode with no luck.

Any suggestions to help uninstall the jailbreak or repair the phone are welcomed.
Put your iPhone in DFU mode and that should help you restart your iPhone once again. 

To put your phone in DFU mode, do the following:


Connect your iPhone to a computer with iTunes. 
Press and hold the lock button for 10s. 
Without releasing the lock button, press and hold the home button for 10s. 
Release the lock button but keeping holding the home button till the iTunes logo comes on the screen.
Your device is now in DFU mode. iTunes should automatically detect the device in recovery and prompt you to restore it. 
Follow the steps and you should have your iPhone working again.