Why can't I hear sounds from my speakers?

I was listening to music the other day and I think I blew out the speakers or something because the speakers won't play music as loudly anymore. I've rebooted my laptop, and tried playing sound from different websites like youtube or spotify, but the sound is still lacking. I've decided to go ahead and purchase new speakers. I'm looking for a step-by-step guide to help me replace the speakers on my own. Please help. Thanks!