Thank you for your post Safin,
The failure to be able to connect to the Internet can be caused by a large variety of issues see a description here:
Some of the common troubleshooting steps are to restart the laptop; turn the Wireless radio off and on (may be a switch or a key combination like Fn+ F8). Also restart the router, (unplug it from the power and 30 seconds later plug it back in) this to clean the routing table. Also malware like a virus may cause a connectivity issue, try running a system restore to a previous date. See the instructions below: http://windows.microsoft.com/en-US/windows7/products/features/system-restore
Also if you can connect to your network and just not access the Internet then apart from the above also try using different browsers (i.e.: Internet Explorer and Mozilla Firefox or Chrome)
NOTE: The links are being offered for your convenience and should not be viewed as an endorsement by Intel of the content, products, or services offered there.
I hope this helps.