MacBook Pro boot issue
You need to boot into Recovery Mode to be able to run a disk repair in Disk Utility.

Press and hold ⌘+R while booting, once you see the Apple logo you can let go.

Because your disk is encrypted, try mounting it first by opening Startup Disk, and choosing your disk as the start up disk. This should mount the drive.
Then quit Startup Disk and open Disk Utility as below.

Then you should see a menu bar with a Utilities option in it, choose Disk Utility from here and run the disk repair.

Unfortunately, disk failure is a possibility, but it could also be corruption from the system going to sleep while in the middle of doing something.
If you do manage to get back into your disk, I would recommend making a backup as soon as possible, as well keeping a regular backup in general.