I filed my tax return with my daughter on the return; I have to amend the return because I forgot a w2 and in the amend return she isn’t listed why???

If you logged into the same account as the one you used to file the original return then the child should still be there ... if you are looking at the 1040X page 2 part 1 that section is ONLY filled in if you are making changes in that section otherwise it is left blank.   Review the new form 1040 that is also populated ... this will show what the original 1040 should have looked like if you had filed it correctly to begin with ... the child should still be on page 1.