New Front Face Camera Not Appear. [mi Note]

Mar 6, 2015
Hello all.
I've a problem with my Mi Note:
After an update, I lost the switch button for the front face camera.
Tried to install a new camera app, and don't see it again.
Tried to fastboot it, and nothing again.
I tried the hardware test and, on the front face camera, no error but I see the back camera.
I don't know how to restore it.
Could be a driver problem couse was after an update. Before that, the camera works like a charm.
Does anyone have a solution to fix it?!
Or I could only flash the files of the front facing camera..
Thanks a lot