If you boot your PC from a Win 10 installation disk, click Repair your computer, and navigate through the options.
If that doesn't work you'll likely have to restore to a restore point or re-image the machine.
It's likely that there's some conflict between the update and a program/service/driver on your PC. Problem is of course narrowing that down. Short of checking and updating everything, it may just be easier to back up your data, do a clean install of the OS, then run the update and re-install everything.
Make sure whenever you get a change to either back up your machine with a disk imager (i.e. Macrium Reflect) or a snapshot tool (i.e. Rollback Rx)