I have an Airport Express that I use to extend the reach of my wi-fi net work. As of today, its light stay only amber and it is not recognized in the Airport Utility. I`ve tried to reset it with no success, no green light at all ....

A solid amber light indicates that the AirPort cannot even get out of start up mode, almost always an indication of a failed internal power supply.

As a last resort, try a factory default reset as follows:

Power off the AirPort and leave it off for a few minutes

Hold in the reset button on the Express first, and keep holding it in for an additional 7-8 seconds while you simultaneously apply the power to the AirPort

Release the reset button after the hold period and allow a full minute for the AirPort to restart

A slow, blinking amber light would be a welcome sight, since this would indicate that the Express has been reset correctly, and can now be reconfigured again.

If the light stays solid amber though, it is time for a new Express