I changed the battery correctly. Now I get nothing. It hot down here please help!

I would suggest getting a new thermostat. Honeywell makes a great product. Thermostats do fail from time to time, and it sounds like yours may have done just that. If you have the owners manual, you can look up trouble shooting and see if it has any advice, or a number to call for assistance. If no manual, time for a new stat, and keep the manual for future reference. Good luck and please let us know how things work out.