What is the ruling on one who commits an invalidator of Islam out of ignorance, or doubts it and does not inquire about it until he dies, and is it obligatory for everyone who commits an invalidator to repent, utter the two testimonies, and perform ghusl?

It appears you are suffering from waswasah (whispers/obsessive thoughts), so you must ignore them. Fear of hypocrisy is commendable, provided it is free from waswasah. Islamic law only considers someone an apostate if they believe, say, or do something that necessitates disbelief, intentionally and with knowledge. As for the heedless, forgetful, or mistaken person, they are not considered apostates. If you are unaware of yourself having intentionally and knowingly committed an act that nullifies Islam, then you are upon Tawhid (monotheism). Increase in the remembrance of Allah, seeking forgiveness (istighfar), and supplication (du'a): "O Allah, I seek refuge in You from associating partners with You while I know, and I seek Your forgiveness for what I do not know." Whatever acts of polytheism you committed out of ignorance, repent from them immediately. Your Islam is not invalidated by doubt, and the default is the continuation of one's state, especially for someone suffering from waswasah. Ritual bathing (ghusl) is not a condition for the validity of repentance from disbelief. As for the obligation of ghusl for one who embraces Islam, there is a difference of opinion, and the sounder view is that it becomes obligatory if there was something that necessitated ghusl while in a state of disbelief. Ask people of knowledge if you doubt anything, for the cure for ignorance is asking questions, and there is no pronouncement of apostasy except after fulfilling the conditions and removing the impediments. One whose Islam is established with certainty is not removed by doubt, and whoever repents from a nullifier and prays, their Islam is affirmed.