Diagnose what is missing
Open Project Status or Manage Media from File → Project Media. Check the source name and expected location. Reconnect external drives first; a disconnected volume does not mean the source file is damaged.
Locate the same original
Use Locate Original to point Meridian to the moved source. Relinking checks expected content and can refuse a lookalike. Similar names are not proof that two files contain the same media.
After relinking, play a range that is used in the timeline. Check picture, sound, and the beginning and ending of the edit. Review all reported missing sources rather than assuming one successful relink repairs the entire library.
Replacement is a different operation
Replace Media deliberately changes content. Use it only when a new file should become the source, and review every affected edit afterward. A proxy should not be offered as an original merely to suppress an offline warning.
Original-media export needs verified originals. Resolve missing-source errors before final delivery, then collect the project if it needs to travel.