users left the project or company

[shajan]

how to find the users in left the company or left the project in JIRA development, 

[Joe Pitt]

I suggest when you deactivate them you move them to a group called something like 'obsolete users'. But as Nic said, if you're playing catch up it will require manual effort.

[Nic Brough -Adaptavist-]

How are you recording the act of leaving?

If you're not, then all you can really do is look at a user's last login, or for a project, run searches for the last time they updated an issue in it.