MacBook Pro Early '11 endless loading bar on boot up

[Kevsta26]

I just went to start up my MacBook pro early 2011 and now it keeps showing a constant loading bar and once it finishes it shuts off then I turn it on again and it does it again... Any help?

 

[T5BRICK]

Looks like an OS update that failed somehow. Try booting to the restore partition and doing a disk repair.

 

[Kevsta26]

Yeah I think you are right, says the disk needs to be repaired

 

[Kevsta26]

Ugh no! It says it can't be repaired and that I should backup as many files as I can and reformat... I don't want to reinstall everything!!! I don't have the time and I've done it like 5 times before... No clue how this could have happened... I just turned off my computer and when I turned it back on this happens... What do I do