Hard Reset on Nexus S

You may want to hard reset Nexus S if you wish to clear all data from the device and set it back to factory default settings. You may want to perform a hard reset (also known as a factory reset) if you will no longer be using the phone or preparing to sell it. It’s also common to use these steps if you’re experiencing problems with the phone. There are a few ways you can go about doing it. Chose one of the two options below that work best for you.
Note: These steps will wipe all data from the memory of the device. If you need to keep any data on the phone, you will want to back it up before performing these steps.

Hard reset Nexus S using Android menus

If you can access the menus, this is the easiest method.
1. Open Settings and select Privacy.
2. Select Factory data reset.
3. Tap Reset phone.
4. Enter your password if required.
The process will take a few minutes to complete.

Hard reset Nexus S using hardware buttons

This option is recommended if you are unable to access the options via the Android OS.
1. Turn the phone off by pressing and holding the Power button for about 2 seconds, the tapping Power off. Alternately, you can pull the and replace the battery.
2. Press and hold the Volume Down button while pressing and releasing the Power button.
3. Continue to hold the Volume Down button until you see a menu appear.
4. Now tap the Volume Down button to scroll down to the Clear Storage option.
5. Press the Power button to select Clear storage.
6. Press Volume Up to select Yes.
After a few minutes the hard reset process will be completed and you can reboot your phone to factory default settings.

Formatting SD card

It should be noted that the steps above will wipe the phone memory of data, but the information on the SD card is preserved. If you’re selling the phone along with the SD card, you may want to format it with these steps.
1. Open Settings and select SD card & phone storage.
2. Tap Unmount SD card.
3. Select OK.
4. Wait for the Format SD card option to light up and select it.
5. Tap Format SD card.
The SD card will then take a few minutes to format.