gotta love phones, with that shelf life. if i can figure it out, im sure it is easy, i will try a factory reset.
Back up everything you want to keep from the phone first (photos, music, etc.). If you want to back up text messages, it will require an app to do that as they are not available to the end user.
Three options:
#1 - Performing a factory data reset via settings
Go to Settings.
Select Privacy.
Click on Factory data reset.
Check Format USB storage if needed only (I recommend this, but only if you've backed all data).
Click on Reset phone.
Finally, select Erase everything.
(2) Performing a factory data reset using phone buttons
Turn off SGS2.
Press and hold down Volume Up + Home + Power buttons at the same time.
Release all buttons when you see SGS2 Logo.
Android system recovery will be loaded then.
Select wipe data/factory reset. (Volume buttons to go up or down, select with Home button)
Select Yes ? delete all user data.
Finally, select reboot system now.
(3) Performing a factory data reset using dialpad
Warning ~ no turning back after key in.
Bring up dialpad.
Key in *2767*3855#
Finally, SGS2 will be rebooted and factory data reset.