Most likely it has experienced severe engine damage. It's possible that there is sludge in the lifters causing the ticking, or it's possible that there is more severe damage. Change the oil now. Drive it for a few miles then change the oil again. Before you change it you might want to put some "engine flush" in just a few minutes before you change the oil then start it and let it idle.
If that doesn't clear out the noise, drive it until it drops, but keep the oil up and keep it changed regularly.