I've accidentally deleted all of my WordPress site users and now I want to recover those deleted users? IS it possible? I've not created database backup so is it still possible?
When you work with any type of database it is of UTMOST importance to create regular backups. Once you delete something from a database it is gone forever. This is what they teach in the first class of any database course.
Here is a link to a question in DB stackexchange
I highly doubt they can do anything about it, but do contact your webhost to see if they can do anything.