Open Excel, Go to TOOLS | Options |Click on the Folder General and then
uncheck the " Ignore other Applications.

"Dave Peterson" wrote:

Windows doesn't know what program is associated with .xls files?

If yes, I'd try reregistering excel:

Close Excel and
Windows Start Button|Run
excel /unregserver
then
Windows Start Button|Run
excel /regserver

The /unregserver & /regserver stuff resets the windows registry to excel's
factory defaults.

If you get an error message (can't find ....), you could try:
Tools|Options|General|Ignore other applications (uncheck it)

lorraina4him wrote:

Why suddenly can't Windows open my Excel spreadsheet ? It has forgotten which
program created it. How can this be? I am desparate to get help opening it.

--

Dave Peterson