This is probably way 2 late but if u have saved a file by mistake u can use the revert 2 last saved function on the File menu, also check de undo history which I think gets cleaned after a save.. but no harm in checking.

I generaly always make 2 saves of the same file as I go along.. if one gets corruopted I use the other... exemple : test.cpr & test bk.cpr!
Use save as and save 2 both at the same time...

what happens when u try 2 open yer file now?

Z