Everytime I get a call my old wallpaper shows even though I have a new one. I'm trying to find it on my iOS but I cannot seem to figure out where. So I'm trying to track down what folders gets backed up when i backup my iPhone since I have restored it and it's still there. (I'm using a jailbroken device)
I have manually managed to find out what gets backed up and managed to solve the problem :) I downloaded the trial of iphone packup extractor http://www.iphonebackupextractor.com/ and found what I was looking for.
Also it seems like I just had to change the lockscreen in the iPhone since the file called LockScreen.jpg was the picture I was looking for but since I had another lockscreen using winterboard I didnt think of this.
Good luck to anyone else who has problems similar to this.