Unlocking MacBook Pro 2012

My MacBook Pro password suddenly stopped working and I never generated a recovery key either. When I shut down the MacBook and reboot pressing the command +s keys, the rebooted black screen quickly disappears and takes me back to the enter password page. Likewise, when I reboot pressing command+R keys, MacOS Recovery page opens but that too only gives Enter Recovery Key option. The Mac OS Utilities page does not open nor there are any options in the tool bar. How can I overcome these issues to unlock my MacBook? I have an i Ph , another MacBook Air and I pad 2 . I tried Apple ID route to reset the MacBook Password but that option also does not come in my MacBook. Also, it is a single user MacBook so I don't have Admin or multiple user log in options. Please guide.