xlet-settings.ui: 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/share/cinnamon/cinnamon-settings/bin/xlet-settings.ui - from package: cinnamon-common

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

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