Can i still amend my tax refund if..?

I did my taxes through turbotax and had 2 dependents. after i was finished, i was going to get a specified amount and i submitted it. but after i submitted it (which is when i cant cancel anymore) i realized it "unchecked" the child tax credit and im not getting the amount i was going to get anymore, instead, something lower. both childs qualified but i dont know why it unchecked them, so now i lost a lot of money because of that. can i still fill out the 1040X and get the rest of the money i could've gotten from the child tax credit?