Thank you Steve. I'm using Access 2007. I figured it out...I had it locked.
Went into access options & miraculously everything is back to the way it
was. I definitely feel blonde.
The reason I felt it important to have this feature in the table view, is
because I'm doing double duty now. Checking math on invoices in excel, then
re-entering them into the Access table. The querys are wonderful...my reason
for wanting to use Access. But because I'm entering info twice, I need it
sorted when I enter it into the table to make sure I'm not re-entering the
same invoice.
I realize it is possible to import...just haven't made it there yet. Still
learning.

Do you have any tips on how to set up the "Invoice No." field to
automatically check to make sure I'm not duplicating any? That would be
wonderful. Thanks again.