Laptop Won't Play Sound - Not Sound Card

Hi, I'm having an issue with my Toshiba Satellite where it won't play any sounds at all - I've tested browser sounds, computer games, Skype, and sound files on my computer itself, and none have any effect. Windows default sounds also don't work.

My operating system is Windows 7, and online searches told me it may be my sound card drivers, but according to my computer, my sound devices are all 100% functional and their drivers are up to date and optimal.

My father suggested it might be a dirty headphone jack, but cleaning it had no effect.

My headphones also now give me static, which they never used to, and unplugging them doesn't help; the laptop speakers play nothing.

It's starting to get annoying after almost a week. The only thing I can think of that's outwardly wrong with my computer is that the very top right corner of the screen had the casing chipped off, so about a half inch of circuitry is visible after the screw. I don't know if that might affect it.

Thanks in advance.