If you messed around with blacklisting drivers and things like that then its
possible you disabled the driver. You might have done this if you were
attempting to load a MS Windows driver via NDISWrapper for instance- or had
some other conflict.
There are also some other things you might have done by accident. If its a
laptop for example there may be an on/off button. Sometimes it is a physical
switch, but more often than not it is a FN key plus one of the F1-F12 keys.
Another possible issue is if you switched USB ports and there are more than
one USB controller. This tends to heavily depend on the controller, kernel
version you have, etc. The problem is there are some systems which have
multiple controllers and depending on the driver its using there could be a
problem related to one of them.
