Switched providers

Your AirPort Express was configured to use and remember the network settings provided by your "old" Internet Service Provider (ISP).

So, the AirPort Express is still looking for the "old network...and it cannot find it,,,,. since it is no longer there. In effect, the Express is now lost and does not know how to find its way.

So, the Express must be reset to erase the "old" network settings, so it can then be programmed with the correct settings to join your "new" network. An Ethernet cable is not required for this procedure.

With the Express powered on......hold in the reset button on the Express for 7-8 seconds and release. Allow a full minute for the Express to restart to a slow, blinking amber light status. Now the Express can be programmed again to join your "new" network......just like you did when you set up the Express to join your "old" network.

Your profile indicates hat you are using a mobile device.....iPad Air. Is this the device that cannot "see" the AirPort Express?

To double check......

Tap Settings on the home screen of the iPad

Tap WiFi

Look for a listing of Setup New AirPort Base Station

Tap on AirPort Express

If you are using a Mac......

Click the WiFi icon at the top of the screen

Look for New AirPort Base Station

Click on AirPort Express

In either case, that will get the setup "wizard" running so that you can reconfigure the Express.