Excel Sheet Uneditable on certain pages

I am unable to edit a spread sheet. All the cells are locked. If I click on the cell to edit
I get two circles at the bottom the cell. I can Type in that cell but it looks like it is writing over the top of the cell. The work sheet is unprotected. File/Options/advanced shows editing is
allowed. File is not read-only. I can edit the other pages in this file.