Hello, about the background path of SMS on iphone4.

Is your PNG in a special format? If not, use PS to process the pictures you need.

Don't delete it directly on the mobile phone, first back up the original to the computer, and then rename the files on the mobile phone.

Upstairs, don't ask others to delete the original files in your mobile phone in the future. Very dangerous. Next time you want to go back to the way you were, you'll die all over the world.