timing belt stripped on 2004 Nissan Frontier

My truck has 82000 miles,and recently got stalled .I found timing belt having several teeth missing .My engine just knocked off while driving (coasting)_@50mph.There was no loud explosions ,do you think my valves is damaged?

Asked by for the 2004 Nissan Frontier
I have never seen the older engine (VG30E) not do serious damage even braking the valve guides in the head when the t/belt breaks. The VG33E is an interference engine as well.
Take out all the spark plugs. Remove the upper timing cover. There are punch marks on the rear timing cover the passenger side sprocket has a corresponding mark at approximately 11:00, the driver's side sprocket has alignment marks at approximately at 2:00 o'clock, the crank pulley should be at TDC. You will have to delicately move the crankshaft pulley bolt getting the pistons down the bore so as not to make contact with valves.
Your engine has hydraulic lifters. Its going to be difficult on a V6 to move the pistons, and both camshafts and not at some stage make piston to valve contact.