sshd: 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/sbin/sshd - from package: openssh-server

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

On Debian possible default full paths are:

/usr/sbin/sshd - from package: openssh-server

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

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