Simply replacing the timing belt won't suffice; a thorough inspection of the engine is crucial *before* attempting to start it again after a timing belt failure. The damaged components need to be identified and repaired or replaced, otherwise attempting to run the engine could lead to catastrophic damage.
It's important to consult a mechanic to accurately assess the damage and provide a cost-effective repair plan. The cost of the repair will depend on the extent of the damage—it could range from relatively inexpensive (if only a few valves need replacing) to extremely expensive (requiring head replacement, machining, etc.). In some cases, the damage might be so extensive that the cost of repair outweighs the value of the vehicle.