I have very recently converted to a MacBook Air from a PC and have a 1.3mb .xls file which 1 week ago Numbers happily opened, edited and saved in its own format.
Today, when I opened it it was corrupted. So I have been trying to open the original .xls file again and the Numbers message is simply 'the file will not open'. No explanation, no clues as to why.
I can still open another (very much smaller and simpler) .xls file but don't know what to do next...