Remnant of an image on LED screen of Samsung Galaxy S2

My friend recently had this sort of remnant of a message on her screen that doesn’t go away. I can’t really describe the problem but I have uploaded an image for reference.
The screen was captured on a plain white background and you can see some sort of a message window that shouldn’t be there. If you know the problem or how to remove it, I would appreciate it.
http://s1310.beta.photobucket.com/user/patrickian01/media/IMG_20130302_111347_zps84013d24.jpg.html
previously, there was the same thing on the bottom part of the screen, but now, It’s gone and this one replaced it.
Answer #1
I suppose that looks like a screen burn in or a retention issue!
AMOLEDS are infamous for them!
What you would like to do is to switch off the phone display for a while!
Maybe 4-5 hours and then use again!
If it is a retention issue, it will probably be gone but if it is a screen burn in issue then sorry you’ll need a screen replacement.
Answer #2
will try later then i will update thanks
EDIT: Tried turning it off for 5 hours but still had no effect. Any other options out there besides changing the screen is appreciated. thanks for those who tried and will try to help.