Phone wont turn on please help iPhone 3G

You need to get some charge in the phone, either via your computers USB or the wall charger.
Then, you need to connect the phone to iTunes where it will - most likely - require a restore as the update did not finish installing correctly. Follow the prompts in iTunes and it will get your phone back to operable status.
Keep in mind that as you are restoring, the items on your phone will be those stored in the latest back up. As it backed up before starting the update process, you should notice no change.
Mac Pro, 20 Cinema Display, iSight, MacBook Pro Unibody Mac OS X (10.6.2) iPhone 3GS 32gb, iPod Video 60gb, Time Capsule, Apple TV, Snow Leopard Beta Test

Thanks a lot. Something is wrong with my iTunes because my dad plugged my phone into his computer and it fixed it immediately so hopefully itll work. I couldnt get a charge onto my phone, I had it plugged into the wall for almost two hours and nothing happened. But thanks a lot hopefully it works soon!
Windows XP

Sounds like your cable is bad.
Lenovo T-60, Intel iMac , Dell/Ubuntu 8, iPhone 3GS 3.1 Windows XP Pro Leopard 10.5.4

What else was different? Were you using the same cable?
If the wall wasnt charging it its probably an issue with the cable or the adaptor. Test both and see which is not functioning. Take the other back to an Apple store for replacement.
Mac Pro, 20 Cinema Display, iSight, MacBook Pro Unibody Mac OS X (10.6.2) iPhone 3GS 32gb, iPod Video 60gb, Time Capsule, Apple TV, Snow Leopard Beta Test