That is the correct procedure and if there is no previous version, its not going to be possible to recover it sorry.
Its not like deleting a file which can be recovered, as its only marked the data for deletion.
With this you re-arranged the data for the file by overwriting it which is why it cannot be undone as the data has been completely changed.
Its the difference between overwritting and deleting.
I would advise you consider a service such as www.dropbox.com
you install the software and you see a new dropbox folder.
Always work from that folder as its both backed up online and versioned, so you can always revert to a previous version in this event.
If you would like any additional information or assistance, please do not hesitate to let me know.
And if you can take a second to rate my service by clicking one of the smiley faces then submit, that would be greatly appreciated.