The iPhone could not be synced because this computer is no longer authorized for purchased items that are on this iPhone

This first appeared on the laptop, i tried on a computer later but same error appear again. I tried almost all tips someone says it works but nothing.. I changed my Apple ID but always same problem. When i try to authorize my computer it says my computer is alredy authorized. Even deleted SC Info folder...same. If anyone knows how to fix this let me says it would be much appreciative. I don't speak english very good so I hope you understand me. Thank you.