user's facebook photo hasn't hanged in years - why?

maybe the girl no longer using her facebook anymore, some time people forget about that they had facebook or forgot to deleted their account . or the person isnt able to use her facebook, she might had moved out of state where she couldnt get any internet access . that happens alot of people. also can be she had made another new account and forgot her last old password for her old fb . doesnt remember it . i dont know why you bothering about it if you had blocked her at one stage issue you had with her at first . its not really a big deal anyways alot of people doesnt have facebook anymore they dont want take risk of having one. facebook does waste your freedom and lifes so there no point of keeping it if you are not always using it everyday or every time. 

Your old friend have do not change the profile picture, so profile picture is same for now.

They have not Updated there Photo in years thats why 

Why are you bothered if you're no longer friends?  It really makes no difference.  I haven't changed my photo on facebook since I opened and account on there ... and I'm not sure how many years that's been.

Because the user in question hasn't changed her photo.  It's not required.

She has no desire to change it.

Or

Million other reasons.