MacBook Pro won't boot up starts and then restarts
My MacBook Pro will not boot up. Power comes on makes the sound, the Apple Logo appears and starts the boot then goes to black screen with out booting up
MacBook Pro, iOS 11.2.2
What model? In any case it sounds typical of a corrupted volume. I had that happen at the end of last year when I forced a power down after a freeze. I'd been able to do that at least 100 times but this time it would start, get to the same point in the progress bar, and then shut down. For some people it might restart at the same point or perhaps just hang forever. The vast majority of improper shutdowns self-repair, but not the rare one can't.
You could see if you can run recovery or internet recovery on your machine and see if Disk Utility can repair the volume using the "First Aid" function. Instructions are here:
About macOS Recovery - Apple Support
When I did it I got a message that my volume couldn't be repaired and that I should try and copy over whatever data I could. I could really do that but had a cloned drive as a backup that I used to restore to a new hard drive, although I replaced it with an SSD later that month.
You might have options depending on what model computer you have. The older ones with SATA drives are easy to just replace the drive and then deal with trying to recover data later.
I'd recommend setting up an appointment at an Apple Store for an evaluation, which will be totally free.