Well if the house door at the front is frozen then I hope someone is home to let me in! If not then I go find the back door key trudge around the back (usually through a couple feet of snow) and go in that way.
If the vehicle doors are frozen from let’s say freezing rain then I remote start my vehicle and hope the heat inside warms the vehicle enough to soften the ice encasing the vehicle. Sometimes condensation freezes the door seal to the vehicle, and again hope the vehicle warms it up enough to melt it.
If you don’t have remote start then you have to either wait for the sun to melt the ice or carefully chip the ice but you run the risk of damaging the paint doing that!