Miataranai is similar to mituskaranai, both translated as something not being found, but miataranai can be used when you first become aware it is missing (Oh, it isn't there, Oh it's gone) and mitsukaranai only after you've actually searched and still can't find it. I've never personally come across mitsukaranai that I recall, however, so it's probably pretty rare. Mitsukerarenai would be "I can't find it."