Factory reset is your only option and since you only had the phone a week yoi wont loose much.
Turn the Galaxy S5 off.
Now press and hold the Volume up button, the Home button, and the Power button together until you see the Android on screen.
Now use Volume down to highlight the wipe data/factory reset option and press the Power button to select it.
Use Volume down again to highlight Yes – delete all user data and press Power to select it.
Wait until you see the reboot system now option and then use the Power button to select it.
When the S5 restarts it should be completely wiped and ready to set up again.
Posted via the Android Central App
11-22-2014 05:57 AM