Answer to "Why is there no sound even when the volume is up?"First check to make sure that any headset or listening device is not plugged in. The speaker is automatically shut off while such a device is plugged in. Simply disconnect the device to enable the speaker again if this is the case. If this is not the case, your speaker is most likely damaged and would need replacement in order for your device's audio to work.
Answer to "Why is my screen frozen? It doesn't look broken."It seems your digitizer may be broken. I suggest powering off your device and then looking for cracks under your screen's surface to be certain. If any such cracks are found, your digitizer is damaged and will need to be replaced.