Display not working after choosing nvidia driver

I had 2 nvidia GT1080 graphics card in my Ubuntu 16.04LTS m/c (with a single monitor display) , never used it so far.
I went to software and updates in settings, additinal drivers tab and an option was already chosen (using nvidia driver-version 384). I chose restart the machine. After this , my display monitor has stopped working, it shows going to power saving mode. What is wrong here? How should I get back my display working fine?