See solution in other versions of Excel:
Question: In Microsoft Excel 2010, I have a spreadsheet that has frozen panes. How do I unfreeze the panes?
Answer: Freezing panes could hide rows or columns, or cause the column headings to always be visible even after scrolling.
To unfreeze panes, open your Excel spreadsheet. Select the View tab from the toolbar at the top of the screen and click on the Freeze Panes button in the Windows group. Then click on the Unfreeze Panes option in the popup menu.
Now when you move around in your spreadsheet, columns and rows should display as normal.