Invulnernable Cell

[Blank_Cell]

I've run into a cell where I can see the contents but can't clear, delete, format or copy it,
Contents of other cells can be copied over top but when the cell is deleted or cleared, the original untouchable contents are back!
I've tried the basic HOME>CLEAR>CLEAR ALL and DELETE.
Any suggestions or links to explanatory info would be appreciated.

 

[shg]

What's the file extension?

Is there code in the workbook?

 

[Blank_Cell]

File extension is .xlsx

Not sure about whether there's code in workbook. I certainly don't know enough to deliverately create any and rest of family is even more clueless.
If it helps at all, the text in cell is left flush and takes the form of "Balance: $1111.11"

 

[lsemmens]

Is the sheet protected? Which version of Excel?

 

[Blank_Cell]

Version is 2010.
Review>Changes>Protect Worksheet has checked boxes for both "Select locked cells" and "Select unlocked cells"; Protect>Workbook has checked box for "Protect structure"

 

[Blank_Cell]

I stumbled into a fix: Inserted substitute row, copied needed data and deleted the previous entire row containing "infected" cell.

Still would like to know how the original cell's data became unreachable and unchangeable.

If anyone has run into this, pls advise. Thanks to Shg and Isemmens for helpful responses.

 

[Macropod]

Without actually seeing the problem worksheet, it can be difficult for anyone to diagnose the issue. Can you attach a workbook to a post with the problem content (delete anything sensitive)? You do this via the paperclip symbol on the 'Go Advanced' tab.