Actually, there were 13 tribes because of the 1/2-tribes of Manasseh and Ephraim. Also, the idea of ten tribes becoming “lost” is not accurate. Four of the tribes remained in the South—in Judah—after the destruction of Samaria by the Assyrians in 722 BC. The South included Simeon, Benjamin, Judah and Levi in large numbers. In addition, of the other nine tribes, none were truly lost. Refugees from Samaria ended up in Judah. Add to that, when Sennacherib deported the Northern tribes, he did not deport literally all of the tribes. There were remnant members of all thirteen tribes. Some of them mixed with the peoples that were exiled into the former Samaria, creating the Samaritans None of them were completely lost. Even today, Jews can identify descendants of the other tribes, like Zebulun and Naphtali.
It is simply not true that one tribe represents the whole of Israel. If anyone told you this, then they were giving you untrue information. In the time of Jesus, members of Levi (Joseph, the father of Jesus), Benjamin (the apostle Paul) and Judah (Mary and Jesus) were still very important and influential in Judaism. Other tribes were influential as well.
In any case, God is powerful and God is in control. God is more than able to maintain the integrity of his inspired canon of Scripture. It is God who determined what entered into the canon of the Hebrew Bible and it is the will of God that this Scripture is protected from significant. How do we know that the Old Testament is the scripture of all the Israelites? Ask any Jew today—whether descended from Ephraim, Manasseh, Benjamin, Levi or Judah. All Jews will tell you that what we call the Old Testament is the inspired Scripture of all Jews.
Let us be honest about what is going on here. This criticism is coming from a Muslim source. Most (but not all) Muslims have no intention of engaging in an honest evaluation of the Hebrew Scripture. Their only intent is to destroy your faith in the inspired Old and New Testament. I advise you to not listen to such disingenuous and dishonest people.
John Oakes