if you're missing /dev/dsp, it's imo because of you haven't loaded the correct modules; these must first be enabled in the kernel while installing it or updating it (either built into the kernel itself or as modules...but that they are there). if you've compiled them as modules, as they usually (?) are, try
modprobe -l | grep sound
and see what you get - these modules are for sound and from these you should pick the ones you need (if not all). when you think you know what they are, or just wish to put everything up, modprobe the ones you want:
modprobe <modulename>
where modulename is the name (without any paths or anything...like if you found a module line like this via modprobe -l: "/lib/modules/2.6.1/kernel/sound/oss/sound.ko" you load the module by giving "sound" as it's modulename (without quotes) - the complete line would be then
modprobe sound
try doing this for the modules you think you need (usually something like sound or snd, and any that has your card's name in it
or parts of it)
when you've modprobed a module, check if /dev/dsp has appeared. continue until you find the one which gives you the dsp device, and then add it to the list of modules that are autoloaded in bootup.