Respected Manorajan,
Me too had d same problem but i solved it later on myself.
Here's it how to :-
1- Make sure u have intel network driver installed i ur windows it pc. Download it ( on any other pc and transfer and install it into this one) and install it in ur respective windows 8 pc. Here's the link to download it :- http://drivers.softpedia.com/get/NETWORK-CARD/INTEL/Intel-Network-Adapter-Driver-172-for-Windows-8.shtml
Den download realtek lan driver from here install it http://drivers.softpedia.com/get/NETWORK-CARD/REALTEK/Intel-Realtek-LAN-Driver-80030730-for-Windows-8.shtml..if in installing theres any error ignore it..dont panic and reinstall..as it will already be installed
2-unplug your LAN cable and wireless connection
3-Go to network and sharing center den on d left side click on change adapter settings left clik on intel network adapter
4-Go to "Ethernet Adapter local area connection" properties and deselect '' Internet Protocol Version 6 (TCP/IPv6)''
5- select **"**Internet Protocol Version 4 (TCP/IPv4)"
And press Properties button
6- select "Use the following IP address:" option and set this ips
IP= ''ur ip address''
subnet mask=255.255.255.0
default gateway = your router ip (you can recheck all dis from any other pc having a successful conection wid dis same one by checking the properties of d connection or from any smart phone like any iphone or android mobile if it is used as a wifi too by seeing staus/properties of ur respective wifi name )
7- from second section select "Use the following DNS server addresses:"
set**"PreferAlternate DNS server:"** your router ip which u entered in ''default gateway'' above. press ok and try to connect through lan then wireless