I have a large excel workbook with two sheets: sheet1 with old values, sheet2
with new values.

Most of the values in sheet2 can be found in sheet1, but not all.

What I want to do is compare the values from sheet2 with sheet1 (are the
values in both sheets)... if they are: compare the complete row against
eachother. (so all the columns of the particular row should be checked)

If they aren't: display a message that the file hasn't been found.

How can this be done?

Any help is appreciated.