In most circumstances that involve Chromebook speaker issues (especially in Chromebooks, as they tend to be weak) the problem with them is that water has gotten into them or they have been tampered with. If this is the case, you should buy a new set of speakers. The other possibility: If you have taken your Chromebook apart before, you may have forgotten to plug your speakers back in or plugged them in the wrong area. It depends on what Chromebook brand and model you are using, however. Then again, it may be something as simple as you have blown them out by playing heavy metal too loud.

Ideally, you can reinstall the GRUB/GNU boot firmware from a simple file. If you want to install the bootloader, go to http://ftp.nl.debian.org/debian/dists/te...-amd64/current/images/netboot/ and click on the mini.iso file. I believe this is the bootloader file.