When I was a younger man, I used to walk past the British Isrealite bookshop. One of the questions asked by such is what happened to the 10 tribes of Israel when the kingdom of Israel disappeared. We do not need to look far: for scripture has an answer. They were joined with Judah, in one kingdom. The question remains as to when this will come to be, noting that the restoration under Ezra and Nehemiah and the rebuilding of the temple ended after the Maccabean restoration when Titus destroyed the second temple. The children of Israel, however, will become one. And into that oneness will be grafted those who have believed in Christ, the son of David. His kingdom is to come, and it will never end.
15 The word of the Lord came to me: 16 “Son of man, take a stick and write on it, ‘For Judah, and the people of Israel associated with him’; then take another stick and write on it, ‘For Joseph (the stick of Ephraim) and all the house of Israel associated with him.’ 17 And join them one to another into one stick, that they may become one in your hand. 18 And when your people say to you, ‘Will you not tell us what you mean by these?’ 19 say to them, Thus says the Lord God: Behold, I am about to take the stick of Joseph (that is in the hand of Ephraim) and the tribes of Israel associated with him. And I will join with it the stick of Judah, and make them one stick, that they may be one in my hand. 20 When the sticks on which you write are in your hand before their eyes, 21 then say to them, Thus says the Lord God: Behold, I will take the people of Israel from the nations among which they have gone, and will gather them from all around, and bring them to their own land. 22 And I will make them one nation in the land, on the mountains of Israel. And one king shall be king over them all, and they shall be no longer two nations, and no longer divided into two kingdoms. 23 They shall not defile themselves any more with their idols and their detestable things, or with any of their transgressions. But I will save them from all the backsliding in which they have sinned, and will cleanse them; and they shall be my people, and I will be their God.
24 “My servant David shall be king over them, and they shall all have one shepherd. They shall walk in my rules and be careful to obey my statutes. 25 They shall dwell in the land that I gave to my servant Jacob, where your fathers lived. They and their children and their children’s children shall dwell there for ever, and David my servant shall be their prince for ever. 26 I will make a covenant of peace with them. It shall be an everlasting covenant with them. And I will set them in their land and multiply them, and will set my sanctuary in their midst for evermore. 27 My dwelling place shall be with them, and I will be their God, and they shall be my people. 28 Then the nations will know that I am the Lord who sanctifies Israel, when my sanctuary is in their midst for evermore.”
Ezekiel 37:15-28, ESV
Leaving the question of Israel aside (it takes up too much churchian energy) we need to look at the acts of preservation and restoration that God chooses to do. He preserved Israel despite their actions. He can preserve us. We should not be dismayed or despair. For any revival is not our doing. It is the work of God.