vtwm: 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/vtwm - from package: vtwm

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

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