Hi @MamaC,

Hope your day hasn't been too troubled by this inconvenience. I'm sure we can figure out what went wrong. 

Since you changed your network password, your phone may be trying to connect to another network while you are configuring the device. Preventing your device from changing network during setup can fix this issue. 

The best way to reconfigure the device, however, is to proceed through the Web UI here is a similar Range Extender and a guide on how to do so: 

How to log into the web management page of the range extender?

If you are still unable to configure the device and access your network, I would recommend resetting the device and proceeding through the initial configuration steps for the device. This will reset the device to factory defaults and will allow you to connect the device to your network using WPS, the Web UI, or the Tether app. 

If none of the above helped, or you need further assistance, can you let me know some more information such as the router model, what method you are trying to change the password with, and how do you normally access the range extender settings?