Hi Chris,
Check in the 'C:\Program Files\Graphisoft\ArchiCAD 13\ArchiCAD Library 13' folder and see if the file 'ArchiCAD Library 13.lcf' exists. It should be 75.6mb in size. This is the library that ArchiCAD loads.
If it is there, I guess all you will need to do is go into the library manager in ArchiCAD (under File>Libraries and Objects) and 'add' the above file.
If the file doesn't exist, try reinstalling/repairing ArchiCAD.