Sometime forgetful is happening to us. You will log in into your ubuntu with your username and password but then it is a mistake. You can not enter ubuntu. Then you try to remember when the last time you logged in to it. Gee… it was a month ago…. ok… that’s normal if you forgot.
This is a simple step that you must do to handle it.
When the ubuntu menu appears choose ubuntu recovery mode. If your menu doesn’t appear, press Esc button when counting down.
And then choose root as your login user.
at the console root, type this:
It’s mean your will override your password for your user.
That’s it, forget your old password and change it to a new one.