How do you raise a baby red-eared slider if you can't find the mom or dad turtle?

I do not believe that turtles nurture their young past the egg stage (building an appropriate nest). Young turtles are left to fend for themselves as soon as they hatch. The above answer is correct... so the answer to how you raise one is simple. You don't. Leave it alone. In many areas turtles are protected, and cannot legally be taken from the wild and raised as pets. If you found it on the road, or some place that isn't safe - bring it into the bush or near a local watering hole. If the carapace is broken, take it to a wildlife vet and they can take care of releasing it after providing care. go to your local pet store, get reptomin baby turtle food, and all the accessories needed to ensure they have proper heat and filtration. once they become the size of a 50-cent peice, continue to feed them reptomin baby, but also start feeding them dried krill (you can find this in the Walmart fish aisle - of course, you will have to break it into smaller peices with your fingers), and even try feeding them very young baby fish and guppies. with the proper water depth (recommended only being as deep as the width of their shell plus legs fully stretched out), proper uva/uvb light, proper temperature, and proper filtration (to ensure they do not get skin bacteria disease), your baby turtle should be good to go! i would also recommend getting that turtle shell lotion they have to help shells grow strong to prevent softshell disease.