mytop: 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/mytop - from package: mytop

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

On Debian possible default full paths are:

/usr/bin/mytop - from package: mytop

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

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