ntpstat: 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/ntpstat - from package: ntp

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

On Debian possible default full paths are:

/usr/bin/ntpstat - from package: ntpstat

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

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