Lost posts and pages after theme change

But what does the admin show you? Are there posts or pages listed? Are they in the trash? Did you have a custom post type? Were you using a custom theme that created custom post types? Did you disable plugins that were defining custom post types?

the admin panel does not show my posts or pages either, they are not in the trash. I am assuming it had something to do with one of the themes I changed from. I was using a theme with custom posts.

So the posts are still in the database, but the post type is not registered any more.
So you can see them again by going back to the old theme. (This is the main reason why themes in the repository are not allowed to do anything except style the existing content.)

To be able to see them without the old theme, you will need a plugin to define custom posts. You can use one already written or write one yourself (it’s not much code, and you can copy it from the old theme). If you use one already written, you will need to make sure the slug matches what is in your database.

There are plugins to enable showing custom post types in archives also. Your theme should show the custom posts (once registered), but with the same template as any other post. To have a specific template for them, you should make a child theme.

Thank you for the assistance. I Was unable to get access to the database nor posts and pages anymore. So Instead I did file restoration with my cpanel hosting account and re-installed through my directory and it fixed the problem or at least gave me access to all my previous posts and pages.