I am trying to sort through old documents any copy data into a master
spreadsheet. I need to match row lables while doing this. I know how to use
lookup, but this will not work because the old data does not list all labels
and even lists incorrect labels.

For example, my labels a

AA
AB
AC
AD...so on

But the old data labels a

AA
AC (does not even have AB)
A2 (incorrect label)

Thank you for any help!