Follow below steps to get your wifi password:
1) Go to system tray and right click on wifi icon.
2) You will see two options as "troubleshoot problems" and "open network and sharing center". Click on second option i.e "open network and sharing center".
3) A window opens. From window left links, click on "Change Adapter settings".
4) Right click on "Wi-Fi" icon from the window.
5) And from the popup, click on button "Wireless properties" in "General" tab.
6) A new window will open with two tabs. select the "Security" tab.
7) click on "Show character" check box to reveal the password. See the screen shot below: