Computer not working

My windows won’t boot up correctly. The keyboard lights up and I see the Alienware screen but it either goes away and stays black or starts “repairing my pc” then leads me to a troubleshoot screen. I’ve tried everything on there including cod prompt (And entered the supposed right commands) and it just says “no files found”.I went to my last resort of resetting the pc and after reset progress hits 100 it puts me on a screen saying there was an error and it then undos the reset. Please help!