How to change Ubuntu Password:

1) Go to recovery mode & in the list select option 'root'

2) Type the command "mount -o rw,remount /"

3) Next type "ls /home". After entering this command it displays the users available.

4) Now enter the command "passwd (username)"

5) Then you will be prompted to enter new password, even if you are entering you cannot see any visual response.

6) After entering your password twice you can use the command "exit" to return to recovery menu.

Source: psychocats