sorry to plague the forum with my problems but as far as i can tell this is the last one
last night i had sound working and this morning i can't get anything. i had sound through vlc and youtube but now nothing. to my knowledge all i've done is fiddle (unsuccessfully) with dropbox since then, but i don't see how that could affect it
i've repacked my linux-sound using the package manager and i've added my user to the 'sound' group so my /etc/group file looks like this:
don't worry i fixed it, rather embarrasingly the keyboard volume buttons had muted it, but on this laptop (unlike any i've ever encountered) they seem to affect a separate volume control to alsa or pulse, it's like it affects the hardware rather than going through the os (the problem persisted after reinstalls and the use of other distros)