I thin you are faced this issue. After saving all documents and files , closing them and closing apps, i rebooted Mac pro. When it restored excel file wan’t there.
Microsoft Office has a Autorecovery function. This function save your files when there’s a power failure or software crash.
These files are stored on the Mac home drive, in the library (Press and hold the option key when you click the Finder Menu -> Go. Otherwise Library is invisible). In library you can see the folder named Application support. Search and find the¬†Autorecovery folder using the following path.
Finder -> Go (Press Option key when you click) -> Library -> Application support -> Microsoft -> Office -> Office 2011 AutoRecovery
If you knew any other ways to open MS office Autorecovery file location, inform us via comment.