Don't ask me why or how, but I removed /etc/modprobe.d as root. Now for example my soundcard doesn't work anymore. Is there a simple (or not so simple) command or formula to get it back?

Thanks!

Mandrake may have made a backup of a handful of configuration files. Look in the logs for a cron job output.
For your sound card, you could run "alsaconf" as root. I believe it will modify /etc/modprobe.d/sound.

/etc/modprobe.d/blacklists may come from the sysconfig package.\
sysconfig-0.50.9-13.7
jschiwal@hpamd64:/etc/modprobe.d> ls
blacklist ibm_acpi ipw2100 ipw2200 ndiswrapper.rpmsave nvidia prism2 sound sound.YaST2save tv
jschiwal@hpamd64:/etc/modprobe.d> rpm -qf /etc/modprobe.d/ipw2200
wireless-tools-28pre13-20

/etc/modprobe.d/prism2 is also from the wireless-tools package.

rpm -ql -all | grep modprobe\.d
/etc/modprobe.d/ibm_acpi
/etc/modprobe.d/ipw2100
/etc/modprobe.d/ipw2200
/etc/modprobe.d/prism2
/etc/modprobe.d/nvidia
/etc/modprobe.d/blacklist

I'm using SuSE, so there may be some differences.

Thanks for your answer.
Sorry, I didn't mention that I'm using Ubuntu, not Mandriva (so I don't use RPM).
I didn't find a message in the log; it's almost 2 weeks ago I deleted the directory...