I enabled roku development mode and try to check the credentials in a web browser using Roku ip address as per the instructions in this page.But the page was not loading in my browser.
http://blog.roku.com/developer/
My system ip address is 192.168.2.25 and my Roku ip address is 192.168.3.110.
My guess is your computer and Roku are connected to different networks and Roku is unreachable from the PC. Note one is on 192.168.2, the other - on 192.168.3 network. Either you have multiple routers (maybe cascaded) or one router but one of the devices is connected to "guest" WiFi and the other is on secured subnet.
Try pinging 192.168.3.110 from 192.168.2.25 - if it doesn't work, i suggest you re-connect one of the devices to the other's network, so both IPs start with the same 3 numbers. I am not saying otherwise couldn't work, it's just simpler this way.