Anyone got an idea or two how to help?

Trying to re open a spreadsheet I hvae ben working on during the day.
I now get the rror message :

" .xls is locked for editing by ' '. "

Obviously I have seen it before when a name of another use on the network
has a file open and I try to open it but I have never seen it with no name
between the inverted commas.
I also know that no on e else has the file open currently.

Andy