I've not tried the modprobe command by specifying the path to it.
If you are doing that as an ordinary user, you may jsut not have the correct authority to do that.
Usual practice would be to run:
to obtain full root contrlo over your computer. The space and minus sign are very important. Then run:
However, that will only load the ndiswrapper module until you restart the machine, and you may need to do that to get the wireless recognised.
Usual instructions for Fedora suggest that after the 'modprobe ndiswrapper' command you use:
and then reboot.
Hope that helps.