Uploaded doc file suddenly empty. Lost forever or is there a backup? How to recover?

Uploaded doc file suddenly empty. Lost forever or is there a backup? How to recover?

I uploaded a MSWord doc*, opened it with Zoho Writer, edited it and saved with from Zoho Writer ... this worked fine several times, but now the file content is gone, has disappeared. 

Opening with Zoho Writer prompts "Problem with server!" Downloading it as MSWord and opening it shows empty file. On my Zoho Page the file continues to show with a file size of 105kb.


How to recover the lost content? 

URGENT - URGENT [file contains vital data].

Thanks!
Beat