Database Testing on Demo Server

I’ve seen comments, and I’ve already applied possible solutions to the live site to fix this issue.
The only option left is that I need to replicate the live site database to our demo server and then test it properly at our demo server. Then I can find what the actual problem is in that particular case.
We can not test or alter db query completely on the live server because it may cause the functioning of the site
I will ask our server admin to copy live server database to our demo server and let you know
Correct above sentence

Here's a corrected version of your sentence:

"I've seen comments and have already applied possible solutions to the live site to fix this issue. The only option left is to replicate the live site database to our demo server and test it properly there. This will help me identify the actual problem in that particular case. We cannot test or alter the database queries completely on the live server because it may disrupt the site's functionality. I will ask our server admin to copy the live server database to our demo server and will let you know."

That’s Why I want to test it freely at our demo server to findout what query or function actually causing timeout during that order status change process
Correct above sentence

Here's a corrected version of your sentence:

"That's why I want to test it freely on our demo server to find out which query or function is actually causing the timeout during the order status change process."