|Did you Name it before you lost it?|
Did you at any time save the file with a name or was it still "Book 1"
If you did name it, then you may be able to recover some of your work,
if it was still unnamed, then I believe you have lost it.
If you gave it a name then:
Go into Excel
That should give you the location where the autorecover save file is.
Navigate to the location and see if you get lucky.
The location may be a Hidden folder so you may need to change your
system folder settings to allow you to see it.
To see hidden files:
Double-click on the My Computer.
Select: View menu
Click: Folder Options.
Select: View tab.
Scroll down until you see the Show all files radio button and select it.
Might want to read this for some background on how Excel works:
message edited by mmcconaghy