Roll Back on versions of docs in zoho docs - excel doc that I checked out is blank. please help

Roll Back on versions of docs in zoho docs - excel doc that I checked out is blank. please help

I checked out an excel sheet on zoho docs and downloaded it to my desktop but when I opened it it's blank.....when I reversed the checked out doc the hosted doc is also blank.  How do i roll back to hosted docs on Zoho?  Please help - I've been working on the doc for weeks now.

Regards, Paul Walsh