The sound doesn't work,

There are many answers to this question, as I will list below.

1. The speaker could be faulty
2. A(some) wires can be loose or cut in between the speaker and the CPU
3. Some apps will only support headphones
4. High volumes on a some speakers may damage the speaker temporary or permantly

Here are some ways the the problem can be fixed, or resolved.

1. Doing a soft reset
2. Doing a hard reset
3. If the tablet froze unplug it untill it dies, then turn it back on (this my take form a minute to a week, matering on you screen brightness or/and how much battery is left)
4. Push the reset button

If all fails,

1. Bring it to a servive guy and see how much the repairs will cost( if the repairs are more expensive then the tablet itself, get a new one)
2. Find a speaker that you can mount on the back of the tablet that connects using a 3.5mm headphone port or a speaker with an adapter for a 3.5mm headphone jack
3. (only recommended if you give up) Find an awesome way to destroy it (for ex. mounting it with ropes on 2 of your cars and ripping it to pieces or do some target practice and shoot it with something like a 22)