2002 Impala

Turned off engine for a couple of minutes. When attempted to restart car nothing happened. No power to anything. Is there a "master fuse"?

 

Welcome to the forum...
Its possible you have a mega-fuse located in the positive battery cable path to the fuse box, however I would verify that your battery is good, it can read 12 volts and still be bad.
Also check the battery cables then need to be clean and solidly connected...
I would be willing to bet your battery is shot....

 

New battery. Car had no starting problems until today. Even yesterday at 15 degrees.

 

Check the connection of both ends of the battery cables, especially the negative where it is attached to the engine block (Ground) This happened on my 01 Impala once. It was corroded and a bit loose.

 

It could be blown fuse.