What steps have you taken to try to resolve this issue? Can you think back to earlier in the week and remember any setting on your computer that you may have changed?

Make sure your FFXIV game resolution matches your actual screen resolution

Try playing in both fullscreen and windowed mode

Try lowering your FFXIV graphics settings

Uninstall your video drivers, run driversweeper, then install the latest driver package from Nvidia.

Since you're walking the line of minimum required specifications for the game (mainly the video card), it's actually fairly common for an FFXIV update to result in this problem.. I've seen it before. That's not your fault, but it's something to keep in mind.