Curious that you say you think it was working for a little while. If that's the case, it might not be a driver problem. I test drivers of all kinds for a living and if it worked at all, it's unusual, but possible, that the driver won't do its thing.Might try checking for hardware conflicts. Sound card conflicts are common.
If you really think it's a driver problem and you haven't tried their NT4.0 driver, it may work.
Go to:
http://www.dataexpert.com.tw/service/
click on "English" and head to their drivers link. You model is listed but not specifically a Win2k driver there. If they don't have one, there most likely isn't one.
Another try, the industry has been following informal standards and many mfg's will build sound cards to emulate SoundBlaster. You might try a SoundBlaster 16 driver, which is one of their earlier cards. Don't suggest trying newer models if your card is like 4 yrs old or older.
Even the mfg. web doesn't show a Win2k driver, which, unfortunately,is too common of a problem with Win2k. Quite a few companies haven't gotten behind this version of Windows.
Is this a special card? I've never seen these but sound cards aren't too expensive if you can replace it.
Sorry can't be more helpful.