If you stub your toe hard enough can it cause a in grown tow nail to happen?

Very unlikely: A stubbed toe has only a brief small injury. Toenails are hard and slowly growing. They get ingrown when they are cut or picked too short and are slowly bent inward chronically as they grow by overlying skin or tight toed shoes. Stubbing a toe may cause an already ingrown toe nail to become newly painful.

It could: If you stub the toe hard enough, you can cause the distal soft tissues to be cut by a nail edge (in the corner). This causes inflammation and with edema, cause nail pressure into it. See a podiatrist for help.