The two standard steps to start with when troubleshooting an iPhone 4S are to perform a soft reset of the device by pressing and holding the power and home keys simultaneously and to ensure that the iPhone is updated to the latest software version. A phone reset often solves many of the problems experienced with the iPhone 4S. The update can be performed either directly on the device or while it is connected to a computer.
In some cases, it may be necessary to take additional steps to resolve issues with the iPhone 4S. When the phone is low on battery, it lowers its performance in order to extend its battery life. In this case, charge the device to ensure the phone is operating at its normal performance levels. Furthermore, it is possible that the phone is operating too many apps in the background. Try closing unused apps in the background to optimize performance.
Sometimes, regardless of taking all of these measures, the issue isn't resolved. In this case, it may be necessary to perform a system restore. This can be done either directly on the device or when it is connected to a computer on iTunes. Restoring an iPhone 4S almost always resolves any software problems with the device.