Simple Form Entry not workin

I have been using a workbook for several years that takes advantage of the
ribbon based form that uses table headings as form labels. Stupidly, I merged
some cells (actually not in the data entry area but adjacent to it).
Immediately I began to get the message that form entry cannot be used on
merged cells. I reinstated the merged cells but I still get the same message
and am unable to use the form entry method. Can't find a solution anywhere -
even in this venerable forum. Can anyone help me please?
--
John