Car help. Cold out side?

Went to work monday morning, came home under 1/4 tank of gas in it that night. The temp got very cold in the - numbers and the block heater was plugged in. I did not start it up tue because was sick and last thing on my mind. I try ed to start it wed but will not start up. The lights will turn on and it will crank over but will not start. Try ed to jump start it as well but with no luck. Got some gas and put it in and now it at 1/2 tank and again nothen when trying.