I believe the project setting is NTSC-AVCHD-FULL HD 1080i 30, which is what I have used for similar projects unless I changed it without realizing it.
Sorry, the program is Adobe Premiere Elements 13, thanks.
Sounds like a couple of issues going here -- but mainly you've lost your connection to your original MP4 source files.
Doing Save As won't change this source file. It's still your original MP4s. In fact, nothing you do to your project settings will change the fact that your source files are MP4s. So I'm not sure what you mean by "The selected file cannot be linked because its type (video) does not match the original file's type (audio and video). "
Only moving, deleting or changing the location of your source MP4s will cause the broken links you describe. Are you saying that you started with MPEGs but, after you built your project, you changed your source files from MPEGs to MP4s?
Where on your computer are these files located?
The selected file cannot be linked because its type (video) does not match the original file's type (audio and video). "
Probably because Elements does not 'see' the audio.
Delete all media cache in the preferences.
Also go to that folder mentioned in the Preferences and delete the rest manually.
Rename folder the footage is in and relink.
See if that will help.
I exited the program and re-loaded it and deleted the mp4 file and reloaded it and the files were found and I am back on track.
Thank you for your suggestions, I appreciate it!
Glad to hear you're up and running again! Please mark this question as correctly answered.