Game Crashes at Splash Screen

I recently returned after around 10 years off. I've leveled 1 character to 65 and another to 40 in the past several weeks with no absolutely no issues. I played last night until midnight and logged off. I am now trying to log back in at 2pm the next day, absolutely nothing has changed on my system, and the game crashes at the splash screen. I hit play, a few sounds go off go off, and then the crash. I've tried around 10 times, rebooted my computer, followed forum advice - and absolutely nothing works. What changed in the past 24 hours?