Manually recreate the package index. See link below for easy steps.
If the previous method does not work try this alternative method.
Be sure to close your PHPStorm or Webstorm whichever one you use. Then try deleting the .idea folder in the root of your project. Also, check for any other .idea folders which may have been accidentally copied/moved into the sub-folders of your project.
Restart your PHPStorm or Webstorm IDE and create a new project using the same root folder as you previously used.
This should resolve the ‘unresolved’ notices in the IDE.
It the notices do not go away then check to make you are you are not dealing with syntax error, missing module or any other underlying root issue.