fsck.vfat: 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:

/sbin/fsck.vfat - from package: dosfstools

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

On Debian possible default full paths are:

/sbin/fsck.vfat - from package: dosfstools

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

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