play: 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/play - from package: sox

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

On Debian possible default full paths are:

/usr/bin/play - from package: sox

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

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