He mainly worked on the Netgear router, but did something to the machine in question.
I am taking a guess that you have no idea what he did?
Did he have root? Since by default no one can make those changes
except root, unless you changed the permissions to allow it.
It is possible that your problems are not related and by chance
happened after he left, since it was working while he was there.
Start from the beginning.
So find the card "lspci"
Then check ndiswrapper "ndiswrapper -l" (that is a lower case L)
Then "lsmod" to make sure that ndiswrapper is loaded.
Then "iwconfig" and "iwlist" to find the interface name and such.
From there with trouble shooting started you have a direction to go.