During installation, there is usually a sound check - I take it y'ol' Satellite failed that?
lspci and dmesg should let you know if your soundcard is even seen. lspci should tell you the chipset - important.
Now - there are many drivers for Realtek audio cards - the trouble is that the designation "SL 250" dosn't seem to exist. Surely this should be "ALC250"
Anyway - while we're waiting - Toshiba for Linux is worth a look: http://linux.toshiba-dme.co.jp/linux/index.htm
I've just spend about an hour trying all the subtle tricks - nobody in these forums seems to have had trouble with the ALC 250 card, though there are other Toshiba sound issues with other cards (check them out - the solutions may work for you too).
There are no realtek sound cards in the HCL!
Your Toshiba is not listed in the HCL either, but other Satellites are - sound problems are a significant minority: it seems that ALSA does not support the soundcards - only OSS.
The ALC 250 is a AC97 chipset card - perhaps other AC97 chipset drivers will work? (A big deal seems to be made over the ALC 650... but see below.)
But I suspect that the OSS driver is blacklisted which is why you cannot get sound. Have you tried alsaconf?
There's tons to check out there. Get back with what you found.
If you want to have a go getting the card going under OSS instead of ALSA - you can find clues in this thread:
I know it isn't your laptop or your card, but the issue is similar and will have a similar resolution... one hopes.
Have you got oss-emulation going? See the alsa HOWTO: