Open PowerShell as Admin
Right-click the Start menu → Windows PowerShell (Admin).
Run This Script
$folder = "C:\Path\To\Your\Folder" # Replace with your folder path Get-ChildItem -Path $folder -Recurse -File | Where-Object { $_.Extension -ne '.txt' } | Rename-Item -NewName { $_.BaseName + '.txt' } -Verbose
Instructions:
Replace C:\Path\To\Your\Folder with the actual path to your target folder.