car dosnt seem to be getting power?

I went out to start my 73 duster 318 after it snowed. It started right up and idled like normal i went inside to get something and i heard the car just turn off. I then tried to turn the car on again but car has no power? starter doesnt turn, lights dont come on i checked the battery it was bad (dead cell) replaced the battery and still nothing? any one know what i can check?

Thanks for the help
William