Got up this am to boil water on GE Profile smooth cooktop this am. All 5 control knobs are locked off. (Except for two small knobs to select heating area of each burner.) Busted one plastic knob trying to force it. Never had any problem before. Circuit breaker did not switch. Any ideas?

never mind - I got it working again. Just had to push down harder than usual to get to turn. Maybe some spill from making soup yesterday.