Hello my name is***** look forward to assisting and am very sorry to hear that you are having this problem.
In order to reinstall the software you would actually have to bring the device to AT&T as they would have to reinstall it, you would not be able to get the software anywhere else.
If it was frozen or something we might have been able to, but when the software is erased only they can put it back on.
I believe they charge an hours labor for this repair. If you have any questions at all reply and let me know. If not please don’t forget to leave a positive rating for my help - it is greatly appreciated. Please note you are rating me only not this site or your AT&T.