Instagram has not made its way to the Windows Phone platform (despite rumors in the past that stated it would be so), so if one is unable to have lobster, shrimp will have to do. In the case of not having Instagram on Windows Phone, there is a workaround through a third party app that is known as Windows Phone Instance. Unfortunately, Instance seemed to have run into its fair share of issues, showing users a message that reads, “Your username or password has changed.”
Basically, this issue was caused by Instagram as well as Instance, where the former demanded that clients who log into the service must have at least version 4.0 up and running, while Instance was spoofing 3.4.4. Fret not, it is not the end of the world, and there is a solution in store – all you need to do is restart the app a number of times, with the alternative being uninstalling and reinstalling the app, and the issue would be fixed. Has it worked for you yet?