Virtual machine ubuntu system forget how to enter the password

       Hold down the shift key to restart the virtual machine will appear the following interface   

       

Hold the 'e' turn down into the underlying interface

　　

      Change red frame to hook string: rw init = / bin / bash

 

 

 

 

 

Then press F10 to boot and type: "passwd" and username

Then enter the password twice consistent password twice (unseen here password input) you are prompted to enter a new password update sucessfully restart password