Why would my well water cut off for 30 minutes before working again?
Have you listened (or measured) to see if the pressure switch is telling the pump to turn on? If the pressure switch is on and you're not getting water out of the pump you've got issues in the well (low water, bad pump) and you could be damaging your pump. 

If you've got low pressure and the switch isn't on there is a problem with the switch (or tank, but that's a low possibility). Do a little bit of investigation and if you can provide more information we can probably provide a more informed answer.