You can normally reset a router in a couple of ways, the first and probably the most simplest way (although you say you have already tried it) is to hold the reset button on the router. Normally this needs to be pressed in using a fine screw driver, pen or paperclip and should be held until the lights on the front turn off.
If that fails then you can try doing a software reset, go to the routers administration panel (normally accessed with 192.168.0.1 / 192.168.1.1 / 192.168.2.1) and find the diagnostics/maintenance page. On here you should find options to reboot and reset to factory default.
The third method would be to do what is called a 30/30/30 reset which is normally the sure fire way to get it back to 'out the box' settings. To do this you will need to hold the reset button for 30 seconds, then unplug the router whilst still holding down the reset button. Hold it for another 30 seconds and then plug it back in and hold it down for a further 30 seconds, essentially you are holding it down for a total of 90 seconds.
Good luck, if it is an issue with the router then maybe resetting it isn't the solution? If you have any more issues then just reply with another question and I shall try my best to help.
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