wnpp-check: 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/wnpp-check - from package: devscripts

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

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