Have you jump started the car before this happened?
How many miles on your HHR?
First, check the EPS fuse in the under hood fuse box. This fuse supplies power to the power steering motor. Its fuse number 1 and is a large 60amp fuse. If this fuse is good, then most likely you will need to replace the power steering motor. Its located under the dash on the side of the steering column. The motor is held on with 2 12mm bolts. Not a hard repair to make.
GM has had a lot of issues with this motor. They even have a recall on the Cobalt, which has the same motor and the same issue. You may want to take it to your local Chevy dealer and ask them for a "goodwill" repair. They can do the repair under warranty since this has been such a issue with these motors, does not hurt to ask.