grub-kbdcomp: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/grub-kbdcomp - from package: grub-common

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