command-not-found: 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 Debian possible default full paths are:

/usr/bin/command-not-found - from package: command-not-found

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

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