kplayer: 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/kplayer - from package: kplayer

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

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