First of all, assuming you are Ashkenazi and had already eaten a kzayis of bread before stepping outside, you do not need to make a new Beracha when you continue your meal.

Regarding washing, if you only went out of the house for a moment and intended to return, you do not need to wash again. However, if there was a prolonged delay and you were completely distracted from maintaining the cleanliness of your hand, the Biur Halacha writes that you are required to wash a second time and recite a new Beracha of Al Netilas Yadayim.