IPhone 3 won't turn on and it's important?

My dad used to have an I phone 3 where he would put all of his notes on. There's more that 700. Anyways he just got a new iPhone but then the old one he kept wouldn't turn on anymore. We have had it charged for so long and it won't work. We even tried plugging it into the computer, wall, and vehicle, but nothing so it's definitely the phone. Is there Anyway we can get the notes from the thing and do you think that we could bring it to the AT&T store for them to fix it or something somehow?! It's important because there's more than 700 notes and each and everyone of them is important. I'm begging here. Anything will help!

Try to hard reset the Iphone and see if it works. Do this steps:

Hold the sleep/wake button at the top right and the home button at the same time.

Hold them until the screen goes black. You may even need to keep holding them after the red power off slider appears. If it does, just keep holding the buttons.

Once the Apple appears you can let go since your phone should now be rebooting.

If no change with that, then start with a new battery. It is possible that your battery is at the end of its life cycle and no longer holds a charge. Of course there are plenty of other things but any of those would lead to a restore. Battery is cheaper it should be around $15-$20.

If nothing works then bring it to Apple store and have them take a look.