My 4x4 light is flashing but wont go into 4 wheel or low just keeps flashing

With the light flashing, it shows that there is some kind of electronic concern with the shift mechanism that needs to be diagnosed. Not sure how much the cost will be, but it will need to be professionally checked -- by a trusted skilled technician near you. Either a dealership or maybe one of the facilities listed here: https://repairpal.com/repair-shops/toyota-repair-and-service-in-chandler-arizona