Excel can not open de correct file
 

Does anybody know how i should procedure to fix/repair a excel file? IS there
any tools available?

I have a file very big (10Mbytes) that sounds to me very well until
yestarday. After saved it I decided to take a break. So I finished my work
session normally. Half an hour later I came back to the root and tried to
open the related file. I could not believe ... excel didn't get the file
correctly opened - after 2 tries excel could open it without any format -
just numbers. What shall I do?

Tks,
Marcelo