Will need to know some basic things first.
How far does it boot? Does it show the OEM image on boot?
How does it fail (what exactly is the message)?
Was anything changed before it happened?
If you get into the command prompt (presuming you don't have bitlocker), and run chkdsk /r against the drive what happens?
If you are getting a fatal hardware error, it is possible the hard drive died. If you are able to run diskpart on it, what size does it say the drive is? If it is really small, and it is a SSD, that usually, though not always indicates the drive died.