So a few weeks ago I decided to root my Galaxy S3. Recently, however, I started having problems. When I tried to go on the play store, I was asked to log in, and after I typed in my username and password & tried to sign in, a message came up which said 'Can't establish a reliable connection to the server'. This happened with other apps that require you to use a google account also. My internet works fine so I knew it wasn't that. I tried using a different account, and then someone suggested I did a factory reset. I thought for sure this would work, but it didn't, and so I tried to update my firmware which had been reset. I couldn't update however because my phone 'had been modified'.
Does anybody know if there any way I can possibly fix these issues?