A very important spreadsheet has been lost - which is saved on our server as
two departments require access to it.

A colleague today has been inputting information into it and says that they
saved it correctly, before closing it down. However two hours ago when I
myself needed to access this particular spreadsheet it had disappeared. I
checked on another Colleague's computer to make sure it was missing and then
began to search on the computer that the inputting had taken place. I am
certain that this was the only involvement with the spreadsheet all day.

When I attempted to open the spreadsheet from Documents (drop down box
beginning in start), a window opened saying that this file could not be
opened as it no longer existed as it has either been renamed, moved or
deleted.

It is not in the recylce bin - I cannot find it anywhere to recover. I do
not understand why this has happened!