Here's a better way to go about it.
In Windows 10, right-click on the Start menu and select
Control Panel. With the category view selected click on
Network and Internet > Network and Sharing Center.
At the top of the window you'll see a section called "View your active networks" listing your current connection. Click on the blue link listed as "Connections.
This opens a window called Wi-Fi Status. Now click
Wireless Properties and in the new window click on the
Security tab. Here you'll see a text entry box called "Network security key," with the Wi-Fi password represented as a series of black dots.
To see your password click the
Show characters box and your password will appear in the network security key box.
EDIT: Oops. This assumes you are on a computer not a kindle. I'm leaving it up anyway.
For the Kindle, try this app