Forgot passcode one iphone 3g and desperately need to get in, how can i get in without erasing the phone

See the instructions in this support document. If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

You cannot. If you cannot remember the passcode for the device, the only way to continue using the device is to restore it to factory. From there, you can restore to your last backup, but that takes the phone back to the date/time of the last backup. Once you have forgotten the passcode, you cannot open the device, or backup the device.

Twaldon103 wrote:

Forgot my password to my old phone which is a iphone 3g and i really need to get into it without having to erase it. How can i do this?

You cannot.