Were the eyes fully open and could the rat run about on it's legs(not crawling belly)?

A rat will drink out of a water dish and eat dog food and survive. If you give it good quality rat food and a dish of water, it should live and thrive even.

If it refuses to eat or drink, there's either something wrong with what you're offering, the rodent is too young to live without mom or it was ill/injured prior to trying to care for it.