XBEE Pro Modem does not work properly

We have a few Xbee Pro modem. We were able to communicate between two modems for about an hour. Later we tried to change the modem configuration. But something went wrong and the modem stopped working. In the USB modem interface board only the orange LED blinks. While testing the modem in X-CTU it displays " Unable to communicate".
When we change the modem, it works properly.
What can we do about this?

I’d suggest reviewing earlier posts in this forum. You’ll find that other people have encountered the same problem, and you’ll find suggestions for the solution.

If the suggestions don’t work, post again with details of what you tried and what happened.

There was some problem in the modem.
I fixed it by writing the default parameters into the modem.