Samsung galaxy ace duos S6802 incoming call always busy. I try to hard reset nothing happens. Call forwarding are disabled. Please help me to fix.it

When a Samsung cell phone becomes unresponsive or when the device slows to a crawl, a reset may be in order. There are two primary methods used to reset the phone. Users should always start with the soft reset when the phone locks up or programs slow down due to memory or software response issues. A soft reset is akin to a reboot of the machine and usually solves most problems without any loss of user data. A hard, or master, reset is required when the phone completely locks up and becomes unresponsive to any cellular signals. This second and more drastic reset deletes all personal data, preferences and settings so that the device is restored to the original factory configuration.
Perform a Soft Reset
Step 1 Press and hold the power button for 10 to 20 seconds.
Step 2 Release the power button and tap the "Power Off" option under the "Device Options" menu that appears. Tap "OK" to initiate the shutdown.
Step 3 Press the power button again to restart the device.
Perform a Hard (Master) Reset
Step 1 Tap the "Menu" key from the home screen and then tap "Settings."
Step 2 Go to "Privacy" and tap "Factory Data Reset" to review the Factory Data Reset information.
Step 3 Review the Factory Reset options. Place a check next to "Format USB Storage" to clear your device of user data, such as music, pictures and other account settings.
Step 4 Review the disclaimer and verify your changes before tapping "Reset phone."
Step 5 Tap the "Erase Everything" or "Yes" buttons to confirm the reset the phone to factory settings. The device initiates the restoration process to the original factory configuration.
Perform an Alternative Soft Reset
Step 1 Power off the phone. If the phone does not turn off, remove the back cover of the phone and take out the battery. Wait between 10 and 30 seconds and then replace both the battery and the cover to restart the device.
Step 2 Simultaneously hold down the power/lock keys.
Step 3 Release the keys when the Android screen appears.
Tips

• The ATT Samsung SII models have an alternative hard reset that requires you to simultaneously hold down the "Volume Down" and power keys after an alternative soft reset, and then release the power button, bringing up the menu titled "Fastbook, Recovery, Clear Storage, and Simlock." Use the "Volume Down" key to navigate to "Clear Storage" and then press the power button. Press" Volume Up" for "Yes" and "Volume Down" for "No." This will reset your device to its original factory setting.
• A soft reset on a Galaxy S phone involves pressing the "Volume Up" key simultaneously with the power button.
• Some older Samsung models have a reset button located behind the battery cover. Press the reset button using a small, blunt object.

• A factory data reset removes all user data and settings associated with the current account. Make a backup of all data on your device before starting a hard reset.