Some time we get a wifi password for a limited time. But when we cross the limit we have to click on the forget password. Then we think that if we know the password then we could connect anytime with that wifi.
This incident also happened with me. In my private tutor's house there is a wifi router. All can surf the internet freely but in one condition, that is - if the password erase from anyone's phone then he couldn't get the password a second time. But as I test many tricks with my android phone and when I get success I share those tricks to you through helperbus, one day it erased from my phone then I started researching on the web to get the password back.
You can fix this problem by following this small steps and you can easily able to know the password of any wifi in a little bit of time.
To do this you have to have a android smartphone and the smartphone have to be rooted.
If you don't know how to root a android phone ? You can go to ask "Google Uncle".
How to know ?
At first, Download ES File Explorer.(to get it go to Google Play Store, type Es File Explorer and hit the search button > download it)
>Then go to es file explorer.
>Open the menu.
>Turn the root explorer on.
>Open the wpa_supplicant.config file -
Opening this file you can see all saved wifi password on your android smartphone.