Hi I am not very satisfied with my page and I am wondering if reinstalling the I click demo will totally rewrite my customised pages in the child theme
This has not answered my question, the template im using is not very suitable do I need to reinstall the Theme to get all the default templates back as I had deleted most of them. how would it affect my current pages and post already written
Your question is already answered but it seems you didn’t notice it.
On the shared page https://support.shufflehound.com/installing-demo/ it says that the New demo installation method (doesn’t replace site content like pages, posts and images) so your site content won’t be deleted.
Also, in your question you said “my customised pages in the child theme” which I answered below.
The demo content is saved in the database so it has nothing to do with your child theme files.