Hi @Viranatha, sorry to hear you lost some work. That sucks. 
It is likely you’ve got Scrivener set to only keep the 5 most recent backups. This is the default setting, which in my opinion is unsuitable for most people.
Have a look at this post I wrote for another user that explains Scrivener’s various backup settings and my recommendations for each. It was written for Scriv v1, but the only thing that’s changed with v3 are the menu options .
Improving your backup habits won’t help you recover the words you’ve already lost, but will greatly reduce the risk of this happening again.
Best,
Jim