backup
 

servers suddenly stopped holding backup sql
what should I do?

Contact your host would be the first step.

you mean my server host?

Yeah, because backups of the SQL are not a part of vBulletin by default, so it is possibly a server issue.

How are these backups done?

is essentially the backup of my forum.
keep copies of the form in datavase sql file in my root

But how are you taking these backups?

was keeping automatically backup in server

That still does not answer my question.

What steps do you take to make the backup, before it gets stored to the server?

when you get vbulletin has a folder that says do not upload
has a file called vb_backup.sh.

Have you checked your server error logs around the time you run that to see if there are any errors pertaining to it?