not working

I built a little robot car that works with IR Remote but i have a question... Is it possible that i need to use the batteries to power the robot so the little engines work? Isnt the power from the usb port of my laptop enough? I tried making it work but it just wouldn't go anywhere, i need the...

I have an LM386 and a 3w 4 Ohm speaker, and I've tried every possible schematic, and nothing seems to work. The sound quality is poor when I make the speaker audible, by turning the volume up. What should I do?