mount: 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:

/bin/mount - from package: util-linux-ng

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

On Debian possible default full paths are:

/bin/mount - from package: mount
/usr/lib/klibc/bin/mount - from package: klibc-utils

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

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