"File does not exist in project folder" indicates that the topic the hyperlink points to is no longer in the current project folder. It was either renamed or removed from the folder using the Windows Explorer, DOS, or by some other file management tool.
Try to Find: Displays the Open dialog so you can browse throughout the folders on your system to locate the file.
Create New: Creates a new HTML file and saves it in your project folder so the broken link can be repaired.