Turn the wifi off and on in the router. Now be sure the security is set to WPA and you broadcast a single SSID.
I've found that helps if it's the usual issue. If not, try another router.
I have a D-Link DI-514 wireless router and I've been using it from past one year, i connect my laptop and Mobile through Wifi with my PC(windows XP), it has been working fine till now, all of a sudden fron last night my Laptop and Mobile are unable to detect the wifi signals(provided, internet on PC is working fine), i tried all possible trouble shooting steps but, none worked for me....can you please suggest me what possibly might have gone wrong, and what am i supposed to do, to make my wifi router working again.
Thanks in advance.