If the inverter is bad, the typical failure mode is no or low voltage applied to the tube. When operational, a backlight gets on the order of 1000V AC from the inverter. A voltmeter is certainly a good way to determine whether the inverter is dead, but note the voltage, and take appropriate precautions. A functioning inverter can bite you very badly! Also note that the voltages may exceed the safe input range of many modern multimeters.
The suddenness with which the failure occurred is consistent with a failed inverter, but additional testing is the only way to be certain.