Try this 1
Try resetting it.
You can find the reset button at the back.
You can use paperclip to push the button. When your router is ON,
just hold the reset button for 30 secs and release it. It will reboot on its own.
It will clear all the settings you have configured in it.)
After resetting connect to your router (through wired) and then configure the
settings. If you have no idea regarding configuring it then make a call to BSNL.
They will guide you.