Laptop not connecting wirelessly to DLink 2750u

[cray]

I have an irritating problem with my windows 8.1 laptop it detects and connects to Internet via my new DLink 2750u modem, through LAN cable not through wireless. Through wireless it sees the SSID of the router but does not connect even though I try to go to settings via 192.168.1.1. This router is absolutely fine with the rest of the devices- iPad, android mobile phone, Chromecast, windows Xp netbook. So I guess the problem is with my laptop only. My laptop connects easily to old modem, android phone as modem. So I guess my laptop not properly configured to recognise signals from this router. I try reinstalling the network adapter driver update etc fruitlessly. I cannot reinstall the operating system since it is updated from windows 8 to 8.1 and I don't have the CD to reinstall the operating system. Need help....thanks in advanvace