How to I manage open apps on my Iphone3?

Have you tried completely rebooting your iPhone? That might reset the Home button.

I just rebooted it now, and it didn’t seem to make a difference. I’ve turned it on and off again just to make sure, and still nothing.

So just so I’m sure, you’re quickly double-clicking the Home button and nothing changes on the screen?

- Hold down the Sleep/Wake button until the Slide to Power Off control appears
– Hold down the Home button until the screen blanks and you’re returned to the Home screen

According to Wikipedia’s article in iOS multitasking, it was only released for the devices from 3GS and up. If your device is the 3G, multitasking is not an option on your device: http://en.m.wikipedia.org/wiki/Multitasking_(iOS) (sorry about the link, Fluther doesn’t like wikipedia’s use of special characters in their URLs)

Chances are that the battery drain is simply the result of the device’s battery reaching the end of its life cycle. Rechargeable batteries gradually lose their capacity over time and repeated charges. The 3G models are now about 4–5 years old. The iPhone’s battery generally can not be replaced by the user – one of the biggest criticisms of the product.

Lithium-ion batteries do have a limited lifespan. On average, count on them losing 15% of their capacity per year under average use; far faster if ever exposed to high heat (like being left in a parked car during the summer). So I have to go with @hearkat on that one.

@Michelleswift – the OP indicated that their “iPhone3” is running iOS 4.2.1. Multitasking became available with iOS 4, but only on the iPhone 3GS or newer. Therefore, if the OP’s iPhone is the 3G model from 2008–10 (which is likely, since 4.2.1 is the highest iOS available for it), it can not perform the multitasking function. If it is a 3GS from 2009–12 (which can run up to iOS 6.1.3), then there may be a hardware issue with the home button.

iOS 4.2.1 will not grant the multitasking that iOS 4.x and newer give to newer models of iPhone. Attempting to multitask with only 128MB RAM and a 412MHz CPU won’t work; Apple knew that and disabled the feature, saving it for devices that had double teh RAM and 50% more clockspeed.

As single-tasking devices, earlier iDevices have no need for a task manager.

Go to your home screen and then just do a fast double click on the button at the bottom that gets you back to the home screen. All the apps that are open will appear, they appear as almost full screen, not a little square icon, and you just move them left or right until you find what you want to close and then slide the pages you don’t want open up towards the top and they disappear and close.

@JLeslie – you are describing iOS 7, which only is available on the iPhone 4 or newer.
The OP has an “iPhone3”, running iOS 4.2.1 (the highest iOS available on the 3G, which can not perform multitasking).

My mistake. I didn’t realize it doesn’t work on I3