"Disk Utility stopped repairing Macintosh HD. Disk Utility can't repair this disk." What now?
With some minor skills and lots of luck you can try to repair it.

While holding the Command-S restart.

When it is done (if it boots) type "fsck -fy".

This will try to repair your disk.

You could spend $120 and get the more professional tool called DiskWarrior.

In any and all cases, back up your stuff.