how do you replace them, mine stop working.

First make sure the problem is the speakers and not that Windows decided to mute itself.

i drop it a few times and now it it is short it out, you can see the wires.

I assume there are speakers you just plug into the sound port in the back of the computer? If so, just get new ones and plug them.

thank youu very much they are, sorry back of my desktop is a bunch of tangle wires, that why they keep falling, can i buy any brand.

Sure, brand is not important. I have a lot of cables plugged into my computer too, but nothing has ever fallen.