This item might not exist or is no longer available – OneDrive
In addition to the above line of text the error message reads, this item might have been deleted, expired, or you might not have permission to view it. Contact the owner of this item for more information. The problem mainly occurs due to The change of name of the default document library on the OneDrive site from ‘Documents’ to some other name. This can be fixed by following the steps described below. SharePoint Designer (SPD) is an HTML editor freeware you can use to create and modify Microsoft SharePoint sites, workflows, and web pages. When you open SharePoint Designer, its Backstage View appears first since it is designed to work only with SharePoint. You must connect SharePoint Designer to an existing site or create a new site in an existing SharePoint environment. Go to SharePoint Designer and open the OneDrive site. If you can’t, you’ll need to enable Custom Script in SharePoint online Admin center.
Go to SharePoint Online Admin center, choose the Settings and move to Custom Script. Here, check the following 2 options.
Allow users to run custom scripts on personal sites.Allow users to run custom script on self-service created sites.
Then, hit the OK button. When done, navigate to the All Files navigation pane on the left.
Right-click the library and select Rename option.
Rename this library to Documents. Close the window and exit. Hereafter, you should not see This item might not exist” error when accessing OneDrive files or folders. Hope it helps!