Hi, @Ataib Ahmad - welcome to the Community!
JQL isn't like SQL; you can't run a COUNT query that returns a number. What you can do is run a query that will return all tickets closed by a specific account, and see how many are returned by that query.
The JQL would look like this:
project = <your project> AND status changed to CLOSED by <the user in question>
If you wanted to further narrow it down by a date range, you could add a "during" clause:
project = <your project> AND status changed to CLOSED during (2019-09-01, 2019-11-12) by <the user in question> ORDER BY updated DESC
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.