My laptop won't start!!!?

Okay, I don't know what I did, but my laptop WILL NOT start! I turn it on and it takes me to the screen where I put a password on my computer (the whole computer), like always, I type in the password and it goes to a black screen that says 'Windows StartUp Failed...' etc. I click on 'Start Windows Normally' and it loops back to the computer password screen. Over and over and over and OVER! So I'm stuck staring at my tiny phone screen right now. I don't know what to do! Any suggestions on what might have happened or how to fix it?