Start with the exact account label, such as “Not found” or “Unauthorized,” and note the date. Google’s ads.txt guide explains how to use the publisher-specific record from the account and place the file at the site root. Do not copy a sample ID into a real file.
The case record should include the domain variant tested, the file path, the returned text, and the date you asked AdSense to check again. Example: the file existed under /uploads/ads.txt but not at /ads.txt; the repair placed the correct record at the root, and the public URL displayed it. Google notes that status may take time to update, so report the immediate public verification separately from the eventual account status.
Use SiteReadyScore to confirm whether the public ads.txt URL can be reached. It cannot confirm the publisher ID belongs to the account or force the status to update. Label any example as illustrative unless it is supported by a real case and permission.
Google source: Ads.txt guide