All text cells converted to #VALUE

Hi,

My mother (of all people) is managing a 2000+ row xls for her real estate business. It has column headers for ID, Description, Price, No of bedrooms etc and is a simple data entry tool with no formulas. Recently she has sent it to me with an issue. All of the cells containing text (inc column headers) are now showing #VALUE!. All of the cells containing numbers have no issues and the numbers are showing correctly. I quizzed her and she doesnt recall doing anything specific that would have done this. I have google searched to no avail - any help from you wise people would be sincerely appreciated!

A very bemused,

Gareth