- columns or rows containing data used in the formula are accidentally deleted.
- a formula has been moved or copied to another cell and the cell references are incorrect.
- data used in a formula has been moved, leaving the function or formula with incorrect cell references
- use the undo feature to recover lost data
- if the data cannot be recovered, re-enter the data and adjust the cell references if needed
- correct the cell references for formulas that have been copied or moved
- correct the cell references for formulas when the data has been moved