Is phosphorus covalent molecular or network?

The answer depends on which form (allotrope) of phosphorus you are talking about. If you heat phosphorus high enough to sublime it (in a vacuum apparatus), when it condenses, it is the allotrope known as white phosphorus. White phosphorus is a molecular solid with P₄ molecules. If you shine UV radiation (even sunlight or fluorescent lights for extended periods of time) on white phosphorus, it will convert to red phosphorus in which at least one P–P bond in the P₄ tetrahedron is broken and P–P bonds between the tetrahedra form to give a network solid. If you heat red phosphorus under pressure or in the presence of catalysts, the most stable allotrope, black phosphorus, forms. It is another network solid (see the wiki link). All these forms are covalent - in white phosphorus the covalent bonds form a molecular structure; the other forms are networks of covalent bonds.