"Nirgends" and "nirgendwo" are synonyms and refer to a location (AT no place), "nirgendwohin" to a direction (TO no place).

"Nirgends" and "nirgendwo" are quite similar. "I can't find my glasses anywhere." -> "Ich kann meine Brille nirgendwo/nirgends finden." Both a correct. "Nirgendwohin" means nowhere. Question: Wo gehst du hin? Answer: Ich gehe nirgendwohin.