If you have no heat or hot water, do a quick inspection of your heating system:
First, check to make sure the power supply is on. Has a fuse blown? Is the gas turned on? Is your oil storage tank empty?
If you cannot find any problems with power or energy supplies, make sure the system is on and the thermostat is set high enough. Next, check the pilot light. If it is not lit, you'll need to re-ignite by following the instructions in your owners manual.
If you still have not isolated the problem, check the pump to make sure it runs. An inoperable pump requires the services of a contractor. You also will have to contact a service contractor if you have sealed heating system.