Argument list for class template is missing

First of all, this is how you should provide a definition for member functions of a class template:

#include "LinkedArrayList.h"

template<typename ItemType>
void LinkedArrayList<ItemType>::insert (int index, const ItemType& item)
{}

template<typename ItemType>
ItemType LinkedArrayList<ItemType>::remove (int index)
{return ItemType();}

template<typename ItemType>
int LinkedArrayList<ItemType>::find (const ItemType& item)
{return -1;}

Secondly, those definitions cannot be put in a .cpp file, because the compiler won’t be able to instantiated them implicitly from their point of invocation. See, for instance,