I appear to have been able to fix the problem myself.
Though it was a little difficult without seeing the System menu options, I made it to System/Appearance/International and set the Language (which was blank) to English (US)...and all the text came back. I'd also set the Character set to Western Europe (ISO)...I don't know if that's the right value for my system however.
Would those settings have been restored if I'd restored my most recent backup, or would that have messed things up?
I performed a reboot to make sure that the start up issue was resolved as well, and I only had to sit though the splash screen once, so I'm a happy guy now (and the WAF will increase when she gets home, and I can amaze her with my debugging skills ).