ndiswrapper: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/sbin/ndiswrapper - from package: ndiswrapper-common

You may install the required package with command apt-get install {package}
Error in other languages:
ndiswrapper: bevel nie gevind nie
ndiswrapper: comandă negăsită
ndiswrapper: comando não encontrado
ndiswrapper: commande introuvable
ndiswrapper: command not found
ndiswrapper: käsku ei ole
ndiswrapper: không tìm thấy lệnh
ndiswrapper: komanda nerasta
ndiswrapper: Kommando nicht gefunden.
ndiswrapper: kommandot finns inte
ndiswrapper: komut yok
ndiswrapper: nie znaleziono polecenia
ndiswrapper: níor aimsíodh an t-ordú
ndiswrapper: no se encontró la orden
ndiswrapper: no s'ha trobat l'ordre
ndiswrapper: opdracht niet gevonden
ndiswrapper: parancs nem található
ndiswrapper: perintah tidak ditemukan
ndiswrapper: príkaz nenájdený
ndiswrapper: příkaz nenalezen
ndiswrapper: команда не найдена
ndiswrapper: командата не е открита
ndiswrapper: 命令找不到
ndiswrapper: コマンドが見つかりません