I stopped working in the USA a year ago and have been residing abroad since then. My old H1B visa is still valid. Now I have in my possession a new I-797 approval notice from a new employer. In the past I have entered the USA using an old employer's valid visa while working for a new employer. But this time I stopped working and have been abroad for a year. Can I still use my old valid H1B visa to enter the USA in this situation? Many thanks.