Hi William Lamb, I can imagine how stressful it feels to lose so many files just by deleting a shortcut especially when Windows updates without warning.
Stop using the PC to avoid overwriting files check OneDrive and Previous Versions for backups try File History or System Restore use a recovery tool like Windows File Recovery or Recuva and if Windows updated look in the Windows.old folder for your missing files.
Were those 578 files stored locally only or were they synced with OneDrive or another backup service before you deleted the shortcut?
Best regard
Lucky