red x's and missiing data and folders on onedrive

Try right-clicking folders with a red X, go to Properties, then to the Security tab.  Change the file and folder permissions and give your account the permissions to sync the files.  You can do that for the entire OneDrive folder.

https://www.youtube.com/watch?v=ufMk-Uj_W8c&t=51s

Hi — before changing sync settings, first protect the data that is still available. Sign in at onedrive.com with the same account shown in the OneDrive desktop app and check whether the missing files are present there. Also check the OneDrive Recycle bin and search by filename. Do not delete, unlink, or reset the local OneDrive folder until you have confirmed the cloud copy.

A red X normally means a specific sync error. Click the OneDrive cloud icon in the notification area, open View sync problems, and note the exact message. Confirm that the correct personal or work account is signed in, that its storage is not full, and that Windows and the OneDrive client are current. Empty-looking folders can also be Files On-Demand placeholders, so check their status icons and try opening one while online.

If the files exist on the web, the local sync connection can usually be repaired safely after a backup. If they are missing on the web too, use the Recycle bin, version history, or Restore your OneDrive where available, and contact Microsoft Support promptly. Please share the exact red-X error and whether the files are visible on onedrive.com.