I opened a video event on the time line in the trimmer when all I wanted to do was increase the volume (my mistake). Regardless, I then opened the file in Sound Forge and increased the volume.
I wish it were that simple. No, the videos are still in the project media file but they have been altered. They are simply audio files now. I don't get it.
General
Name: 009.AVI
Folder: C:\Users\Tony Johnson\Desktop
Type: Video for Windows
Size: 1.70 MB (1,745,408 bytes)
Created: Wednesday, January 01, 2098, 12:00:00 AM
Modified: Wednesday, August 05, 2009, 11:26:28 AM
Accessed: Wednesday, August 05, 2009, 11:08:36 AM
Attributes: Archive
ACID information
ACID chunk: no
Stretch chunk: no
Stretch list: no
Stretch info2: no
Beat markers: no
Detected beats: no
Other metadata
Regions/markers: no
Command markers: no
Media manager
Media tags: no
Plug-In
Name: aviplug.dll
Folder: C:\Program Files\Sony\Vegas Movie Studio Platinum 9.0\FileIO Plug-Ins\aviplug
Format: Video for Windows
Version: Version 1.2 (Build 8619)
Company: Sony Creative Software Inc.
You must tell us what kind of AVI videos these were. It seems that you simply lost the decoder codec for it on your system. Something you uninstalled or overwritten recently.