I had something similar happen; a mother rat that died, leaving behind babies whose eyes were not too long open. I took the lab blocks that I feed to my rats, and moistened them with water, and offered them on a flat platter. The babies learned to eat the moist food and they did survive.. they would lap water from a small dish I put in there.
Others may recommend milk replacer. I would have to see a pic to agree 100% with the recommendation of moist lab blocks, to see if they look "with it" enough; if they still have that dopey, eyes-half-shut look, they may need milk replacer.