Ubuntu forgot the password. How can I solve this problem if I forget the root password!

Ubuntu forgot the password. How can I solve this problem if I forget the root password! -- Linux general technology-Linux technology and application information. For details, refer to the following section. Ubuntu root is disabled by default. During installation, you are not required to set the root password, which is different from the Red Hat system series. To use it, set the password for the root user. sudo passwd root
If the password of a common user is forgotten, use root to modify the password. If the root user forgets it, it enters the single-user mode, which is different from the Red Hat system series.
Enter single user mode: 1. When the system is started to grub, use the up/down key to move to the recovery mode of the second line, and press e (note not press Enter) 2, change ro single to rw single init =/bin/bash and press ctrl + x to enter single-user mode. You can change the common user password or the root password. Press ctrl + alt + delete to restart the instance. (I tried to shut down the instance by using the command. This is the only option to restart the instance ).
I have tried these things and they are also successful. Please try them! I have read some methods on the Internet and tried some of them! Some methods use the Red Hat system series, and some are incorrect!
If not, you can contact me, My QQ 284198471 (principal Ubuntu), hope to help you!