Hi Piedmont17,
Welcome to the Sony Community!
I suggest checking the folders added to the software to see if the folder containing the original files is being managed by the program. Go to the Files tab and select the Add folders option. If you moved the files to a new folder outside of the software, they won't be automatically added to PMH. Mark the new folder to add it to the software.
You may also try running the PlayMemories Settings Initialization tool so the software will automatically read all the video files save din your computer.
If my post answers your question, please mark it as "Accept as Solution". Thanks_Mitch