The Earth bereft of its atmosphere would likely make a new one, because volcanoes are constantly belching out volcanic gasses which would become the new atmosphere. It would be very different in composition from the Earth's present atmosphere, however, because most of the Earth's atmosphere is nitrogen, which is not present in volcanic gasses. The Earth's volcanic atmosphere would be much more similar to that of Venus, i.e. mostly carbon dioxide (the water vapor would get ionized by ultraviolet light and the hydrogen would escape), although it would take a very long time for it to get anywhere near as thick as that of Venus.