mpdroot: 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:

/usr/bin/mpdroot - from package: mpich2

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

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