I cut and paste another part of the file to an existing excel file,
When open the file again, the page is blank and a dialog box states:
"Unable to open file". I saved my work every step of the way. I made a
backup copy and have tried it several times. Each time the dialog box
states : Unable to read file. I opened up a new page on the same sheet and
was able to make the change but I could not correct the original page.

r burns wrote...
I cut and paste another part of the file to an existing excel file,

This is confusing. Are you copying one part of *ONE* workbook and
pasting into another part of the *SAME* workbook? What are you copying
and where does it come from? Where are you pasting it?

When open the file again, the page is blank and a dialog box states:

Presumably you saved the workbook after this copy/paste operation. Did
anything seem amiss during the save?

"Unable to open file". I saved my work every step of the way. I made a
backup copy and have tried it several times. Each time the dialog box
states : Unable to read file. I opened up a new page on the same sheet and
was able to make the change but I could not correct the original page.

Which Excel version are you using? Excel 2002 and 2003 should be able
to repair simpler file corruption problems. Also, just in case this is
a hardware issue, where is the file located on disk? When was the last
time that disk drive was checked for bad sectors?