PC stuck on black screen w/ underscore. What now?

This has happened to me as well. The problem is not because of the updates, it's because windows was shut down "forcefully". When this happens usually the computer takes longer to boot but it finally does so...if waiting (up to 10 minutes) does not solve the problem then press F12 after turning on the PC to bring up the bootable drives list and select your operating system therein. If it still doesn't work, then shutting down during update DID cause a screw in the registry and in shorts you MIGHT have to reinstall.