we are working on a client live store, we need to work on some structure changes of site,we are facing issue for products, need to update data, but as working on live site we are unable to work, please guide us.
You need to product more information on what you need. It sounds like you want to work on the site and dont want customers to see it . You have two options if that is the case.
1. Close the store down for a while and work on it.
2. Duplicate the theme and work on it then post it as main.