H1b stamp expired but I797 is active. How do I travel back to US

I have an existing H1b and had to come to India for an emergency. My H1b stamp on passport expired in June but my i797 and i94 expires next year.

Will I need a new stamp to come back to US ?

I have also read about traveling via Mexico. valid H1b stamp is not needed if you travel via Mexico and have active i797. Could I go to Mexico and then go to US?