qphotorec: 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/qphotorec - from package: qphotorec

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

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