Background

You have a Windows 10 environment with WSL installed and are using a Ubuntu distribution. You forgot the password that was setup when you first setup Ubuntu. You need the password when you install software such as when doing apt install <software>.

So here’s how:

1. Open windows command prompt.

wsl --user root

2. Change pasword for root

passwd 

3. Alternatively, change password for a specific user

passwd <username>

Hope this helps.