mutter: 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/mutter - from package: mutter

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

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