insmod: command not found

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

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

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 CentOS possible default full paths are:

/sbin/insmod - from package: module-init-tools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/sbin/insmod - from package: kmod
/usr/lib/klibc/bin/insmod - from package: klibc-utils

You may install the required package with command apt-get install {package}

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