My pinky toe nail came off. what can i put on it so that it can grow back?

Time: Other than maybe some antibiotic ointment and a bandaide for a few days until the underlying nailbed toughens, there is little you need do. The nail will grow back on its own, but be prepared to wait about 9 months for full regrowth. Also, check your shoe choices. Narrow-toed, high heels are a common culprit of small toe trauma and can cause this to happen again if worn too frequently.

No need : To do anything, in time it will regrow. Might cover with bandaid for a short while.