Select Network and Internet Settings.
Select Open Network & Internet Settings
In the Network and Internet Settings application, select Network and Sharing Center under the Change your network settings section.
Select Network and Sharing Center
You are taken to the Network and Sharing Center. Select the live Wi-Fi connection.
Select Wi-Fi connection
In the Wi-Fi status pop up dialog box, select Wireless Properties.
In Wi-Fi Status pop up box, select Wireless Properties
The Wireless Network Properties dialog box appears. Select the Security tab.
Navigate to Security tab in Wireless Network Properties
In the Security tab, tick the check box Show Characters to reveal the Wi-Fi password.
Select Show Characters checkbox for Network Security Key
You will now see the Wi-Fi password shown in the text box next to Network security key.
Wi-Fi password now is revealed in Wireless Network Proeprties

How to find Wi-Fi passwords to Wi-Fi networks your computer has connected to in the past

Find other Wi-Fi network passwords in Windows 8/8.1/10

The newer versions of Windows have made it more difficult to locate the passwords for other Wi-Fi networks. You wonder why they would do this? Odd eh? Newer versions of applications are supposed to make our lives easier! Harumph! Oh well… onwards to the instructions.
From your Windows desktop, navigate to the Start menu.
Navigate to Windows Start Menu
Click on the Command Prompt application or you can search for it in the menu.
Select Command Prompt
Type in the following command in Command Prompt and press the Enter key:
netsh wlan show profiles
Enter in netsh wlan show profiles in Command Prompt to find Wi-Fi profiles
All the Wi-Fi networks you’ve accessed in the past will appear.
Wi-Fi User Profiles listed in Command Prompt
To find a password for one of the profiles listed enter in:
netsh wlan show profile name=profilename key=clear
For example, we want to see further details about CloudBT-Guest. You would enter in…
netsh wlan show profile name=CloudBT-Guest key=clear
Enter in netsh wlan show profile name=profilename key=clear in Command Prompt to find further details about Wi-Fi Network
In the information presented, the Wi-Fi password will appear next to ‘Key Content’ under Security Settings.
Wi-Fi Network password apperas next to Key Content in Command PRompt

Find previous Wi-Fi network passwords in Windows 7

For Windows 7, the process is relatively simple by comparison to Windows 8 & 10.
Navigate to the Windows Start Menu.
Navigate to Windows Start Menu
Select Control Panel from the Start menu.
Select Control Panel in Windows 7 Start Menu
In Control Panel, click Network and Internet. You would view the layout in the example below by changing the ‘View by’ configuration to Categories.
Select Network and Internet in Control Panel
Select Network and Sharing Center.
Select Network and Sharing Center
In Network and Sharing Center, click on Manage wireless networks.
Select Manage Wireless Networks in Network and Sharing Center
A list of Wi-Fi networks you have connected to in the past appear. Right click a Wi-Fi network you want the password of and select Properties from the drop down. Alternatively, you can simply double click the Wi-Fi network with your mouse.
Select Wi-Fi Network and Properties from drop down list in Manage Wireless Networks
The Wireless Network properties for that Wi-Fi network shows up, navigate to the Security tab.
Navigate to Security tab for previous Wi-Fi Network
In the Security tab, tick the checkbox Show Characters under Network security key.
Select checkbox next to Network security key to reveal Wi-Fi password
The password will appear in the text field next to Network security key.

Sekian dulu deh cara hack wifi lewat COMMAND PROMPT