A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear Srinivas,
Welcome to the forum here.
From your description, it seems that all files are missing in the SharePoint site you access and you have tried all the suggested suggestions and you can't find them.
If yes, given the situation, as there is a specific support channel where our related team is working on helping the users on data recovery in SharePoint Online, I kindly suggest you contact the administrator in your organization and let him open a support ticketto our related team as soon as possible so that they can further help you to see if they can restore the data for you in your environment.
Sorry for that our category may have limited resources on the further data recovery.
Meanwhile, if the issue in your environment is that you can't access the site when you type the site URL https://contoso.sharepoint.com/sites/sitename in the browser. The root cause may be that the site home page has been deleted. You may let the site owner go to the page library to recreate or restore the site home page to see the result.
Thanks for your understanding and have a nice day!
Cliff