If multiple default files are missing, resetting AutoCAD to defaults will reinstall all standard CTB files.
C:\Program Files\Autodesk\AutoCAD 20xx\UserDataCache\Plotters\Plot Styles (Note: This is a hidden folder). Autocad Monochrome Ctb File Download
To make it default: Set it in your page setup or template file ( .dwt ). If multiple default files are missing, resetting AutoCAD
A: You likely have "Plot object lineweights" or a custom page setup that overwrites the CTB. Check the "Plot Style Table" dropdown again. If multiple default files are missing