My icloud was changed and everyone say that it is not possible

Once installed on my iPhone iOS 8.2 with a third-party site is my phone. To do this, phone requested turn off the "find my iphone" and clear all data from your phone. After restarting phone it requested appleid unknown to me, and a message about the theft of the device. This link for reference file i installed https://drive.google.com/open?id=0B_bTUK6mvOMUfjJVOXBSMldwMGQyeHptWlJuMDlnNEFOZH J4Y3NGUWJSLWJoTXNQTWgtelE (I can not remember which of the two it was) Complicating the situation is the lack of documents on the device, only a backup in icloud.