The toddlers were banging on the MacBook Pro, and now the display font is different. Every window that opens now has a font that looks like it was typed on an old manual typewriter with a worn out ribbon. How can I restore the font? Thank you!
Look at the Accessibility pane in System Preferences. There are some settings in there than can reverse text and mess with fonts to assist the vision impaired. Some of those settings can be turned on by a KB combo, and the little tykes may have inadvertently hit on the right KB combo to turn on one of those features.