I have Cydia and Repo666 installed correctly on my iphone 3G. But anytime i get to repo666 it WON'T reinstall. When I hit CONFIRM ,while it's loading i lose both cellphone network and wi-fi. And after reloading it would tell me RESART SPRINGBOARD. When I hit Resart Springboard it will start reloading for a little bit and the phone automatically goes back to the iphone menu.
tI won't just complete the unlocking process anytime I get to that stage (Repo666-Modify-Confirm).
What to do to fix this issue?
Also how to get the phone display APN instead of VPN on the SETTINGS (I believe it has something to do with the phone being locked.)
P.S.: the phone is jailbroken alredy

Modifying the repository itself should have no impact on your cellular service -- I'm not sure why you would be having that issue.

With regard to the "VPN" request, VPN and APN are entirely different / not interchangable / not related. If you had APN editing enabled, you would see "Cellular Data Network" in your Settings.app under Network. VPN will always be there, it's a way for enterprise customers to create an encrypted, secure tunnel between their phone and their enterprise network.

In order to get APN editing, if you're on a carrier that carries the iPhone and supports tethering (and you don't have the tethering plan), you will need something like MyWi or TetherMe, as well as the APN Editing bundle.