Back button not functioning

[Jolene Anderson]

I'm not sure when it started (maybe night before last) but my back button is not functioning. It will light up (as well as the recent Apps button) but will not go back. It makes it impossible to use chrome and many apps.
So far I have done a regular restart, a volume down/power off then tried both the power down and the restart phone options, and even reset to my factory settings. No luck.

Please help!

 

[mikedt]

If it's still not working even after a factory reset, could be an actual fault, repair service required. Is the phone still under warranty?

 

[Jolene Anderson]

If it's still not working even after a factory reset, could be an actual fault, repair service required. Is the phone still under warranty?

I got this phone from Assurion after my phone was stolen. I've had it for about three months I think.