What? Do you have two SEPARATE fields, one name Lastname and other Firstname? Or do you have ONE field with LastName, FirstName? Rereading the original question, I think I made a mistake. You have ONE field. But that's alright. Again, just use the wizard. Now in your form, are you saying that the combobox doesn't open? Or are you saying that when you select a name, that person's information doesn't appear in the other textboxes? You're very unclear.
If you want information about the name you selected, put the following on the OnClick event of the combobox.
Dim R As DAO.Recordset
Set R = Forms![FormName].RecordsetClone
R.FindFirst "Name_ID = '" & Me![ComboBoxName] & _
"'"
Forms![FormName].Bookmark = R.Bookmark
End Sub