My iphone's battery was full in the morning when I see it but it suddenly turn off. I tried to turn on but to no avail. Could someone tell me what to do now?

try reset it. if not work, maybe something wrong with the software or inside the iphone itself.

REplace your data cable.If not working that also.... check you port of iphone.And try different USB port.
Thanks.

Have you tested it with another battery?

Make sure the battery is good.
Make sure the battery is connected to the iphone properly. That is, check the battery terminal.
If the above doesn't solve the problem, then it means the iphone has developed a power problem.

Regards.

Hello!I have a problem with my iPhone 3g battery life, it lasts for no more than 5 hours or so and it doesnt matter what I do with the phone, if I listen to music, talking to someone or even if the iPhone on standby, at night I have to put it to charge because the iPhone just wont last the entire night (on standby) and will turn off.does someone have the same problem or know what to do to fix it?I have the iPhone for like a year and a half and the version is 3.0

Almost same problem here.
It worked perfectly yesterday and this morning, showing almost full battery. Suddenly, in my pocket, it died.

This is not the first time it does that, actually 3 days ago it did the same thing. I charged it up, connected it to iTunes 9 and restored it to OS 3.1 (from jailbreaked OS 3.0.1). Then it worked!
But the funny thing is that it showed battery power was about 75%, then it blacked out.
Also charging the battery gives me a hard time - like it just won't do it.

I suspect the battery to be dead, so I'm gonna try to pull it out - wait 30 seconds - then plug it back in. Anyhow, I'm going to buy a new battery anyway. Suggest you try the same thing, at less you've still have warranty on the phone (I don't).

Hello ! I was in panic attack !!! did everthing and nothing seems to wake up my iphone. I forgot to charge it so battery went full empty, then I plug it on the wall charger, and nothing happend. I let it all nite, and next morning,... surprise !!!!! still the red icon, No battery, the iphone didnt restart!!!! How I fix it?
1-unplug it from the wall charger 2- press middle button and startup button, same time 3-when red battery dissapear, plug the charger. 4_ do this many times. Didnt work for me the first time, but at the end it works !!!!
NOW MY IPHONE IS WORKING GREAT !!!!! GOD BLESS YOU ALL !!!!!!!!

Sounds like your keyboard has died...Try to perform a reboot, and make sure the battery is seated correctly. You will most likely have to get it replaced. I recommend going with a Microsoft wireless keyboard and mouse. Its a lot better than Logitech!!

try fully charging the battery