extundelete: 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/extundelete - from package: extundelete

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

On Debian possible default full paths are:

/usr/bin/extundelete - from package: extundelete

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

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