At First, i was able to access the board but suddenly i could connect. I’ve tried logging in using the IP add but i wasn’t able to access it. I tried using the DUDE but it could detect the IP address. I tried using winbox but still no IP or MAC address was shown. I tried Using also mikrotik neighbor viewer still the problem remains. I have another same board and tried those software and it works. I checked the LED status, it works normally. Does anyone knows what could be the problem? 
thanks..
Assuming neighbor discovery is enabled on the relevant interface, it sounds hung and probably needs power-cycled. After that, you could enable the watchdog, and possibly the ping watchdog (there are two watchdogs), and hope that is able to recover it if it happens again. What version is it running, and is it doing any routing?
hello.. thanks for the reply. we just did a factory reset and it works properly again. 
.. i think the board just hang.. i am new to this device..