Room temperature ferromagnetism in oxide based semiconductors can be attributed to the alignment of localized electron spins,due to defects and/or dopants.In this work, we synthesized pure and manganese doped zinc oxide by a solid-state reaction method, and the defect type and concentration were varied using two different processes, conventional furnace annealing and spark plasma sintering. These defects were characterized by a variety of techniques and correlated with the measured magnetic behaviour in the material. Ferromagnetic like behaviour was observed in the doped samples prepared by furnace annealing, due to the manganese present in multiple oxidation states. Ferromagnetic behaviour was also observed for pure zinc oxide, after spark plasma sintering, where the oxygen vacancies mediated the magnetism. Thus, the magnetic origin in zinc oxide can be controlled by both defects and transition metal dopants. ZnO based inks for depositing thin films were developed by dispersing the respective nanoparticles in an ethylene glycol based solvent with polymeric stabilizer additive using mechanical milling approach.Comparative study of magnetic properties of bulk and thin films was done. Our work shows, this approach can be helpful in designing dilute magnetic semiconductor based devices.