Why am I not getting any power in two legs of my main power?
If you are comfortable doing it, you can take the front panel off of your breaker box and check the voltage of the wires coming in from the meter, but in cases where "one leg is dead" it is usually a problem with the power utility.  In your case it's pretty obvious because you have no 240v loads, but sometimes in houses it can be a confusing and dangerous problem because voltage can travel through a 240v appliance.

I guess it could be a bad connection between the main breaker and the rest of the panel, but we've had several questions on the site about partial power outages and it's generally the power companies issue.