I woke up this morning to a house that has no hot water, but plenty of cold water.
The shower will not work because of no hot water I presume. Everywhere in the house there is cold water for use. I checked the pilot on the water heater, and it is lit. I have lived here for almost four years and never has the pipes froze. I believe the temperature only got down to 27 last night.

"shower will not work because of no hot water I presume" Are you saying that at the shower there is no water at all, neither hot nor cold? Out a pan under the boiler drain, small valve at the bottom of the tank, and open the valve, do you get hot water? Back to you.