If you watch the Nick Jr. Presents shorts around 2000 to 2003 such as Dearest's Painting Dreams, Tortillas & Salsa, Seven Days, Six Nights and Babysitting Baby Brother, there is one short that is currently lost. Baby One Afternoon is the only Nick Jr. Presents short that is currently lost. It's about a baby boy who wears a blue diaper staying at home by himself such as taking a bath and taking a nap at the end.
The lost short has been found and was uploaded to YouTube by RTXwheels. Skip to 2:23 to see the short.