Speakers generally work when they are connected to the radio and not shorted out. You can test the terminals with a multimeter to see if its getting power.
In the Echo - 2002 TV was released on: USA: 2002
Be My Echo was created in 2002.
Echo - 2002 is rated/received certificates of: Belgium:KT
Galeria Echo was created in 2002.
the fuel filter is plugged
Forty Foot Echo was created in 2002.
Echo dot is smarter but google home mini has a better speaker.
For my 2002 Echo it is 3.7 Liters with a filter change.
Open your trunk and check the rear speaker wires - chances are something banged into them and damaged the wiring creating a short. If so, you can fix the wire or clip it (in which case you would lose sound in one rear speaker but your radio will work again).
The 2002 Toyota Echo OBD 2 port is under driver side dash next to kick panel
http://pdftown.com/2000-2002-Toyota-Echo-Service-Manual.html
If the A/C is not working on a 2000 Toyota Echo, the pump may need to be recharged. It is also possible that the belt for this is broken or the thermostat is sticking.