Would the error happen to be "Kernel panic - not syncing: Attempted to kill init!"?
I'd assume that you've either had your filesystem corrupt itself or had the storage device/controller fail. But, since you're making it that far, and I'm assuming this is a SSD, it's probably more likely it's corruption.
I'd start by booting to a USB stick and seeing if you can fsck the filesystem(s) on your drive.