Thanks Tony, For replying the problem has been solved i used a second tv to set the lower resolution setting on my NVR and after applying the setting i rebooted the NVR. Then i pluged the HDMI from my first tv and its working fine now.
I can't start the NVR, the Dahua logo can be seen on the TV screen for a few seconds when i power on the NVR and then the screen goes black and nothing happens. My tv is Panasonic Viera 55CX740_Series. Thanks