Reset A Lost Administrative Password In Ubuntu

                        By default the first user's account is an administrative account, If the user doesn't remember their password you need to reset it.For this

1.  Boot into recovery mode:-

                 Boot up the machine, and after the BIOS screen, hold down the left Shift key. You will then be prompted by a menu that looks something like this

2 . Get the Window like below

3. You should now see a root prompt, something like this:

root@ubuntu:~#

At this stage you should have a read-only file system. You have to remount it with write permissions:

root@ubuntu:~# mount -rw -o remount /

Now we can set the user's password with the passwd command.If you find the user names goto /home.

In this example I will use jagan user's username

root@ubuntu:~# passwd jagan

                                     Enter new UNIX password:
                                     Retype new UNIX password:
                                     passwd: password updated successfully
                                     root@ubuntu:~#