mpif77.mpich: 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 Debian possible default full paths are:

/usr/bin/mpif77.mpich - from package: libmpich-dev

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

Error in other languages:
mpif77.mpich: bevel nie gevind nie
mpif77.mpich: comandă negăsită
mpif77.mpich: comando não encontrado
mpif77.mpich: commande introuvable
mpif77.mpich: command not found
mpif77.mpich: käsku ei ole
mpif77.mpich: không tìm thấy lệnh
mpif77.mpich: komanda nerasta
mpif77.mpich: Kommando nicht gefunden.
mpif77.mpich: kommandot finns inte
mpif77.mpich: komut yok
mpif77.mpich: nie znaleziono polecenia
mpif77.mpich: níor aimsíodh an t-ordú
mpif77.mpich: no se encontró la orden
mpif77.mpich: no s'ha trobat l'ordre
mpif77.mpich: opdracht niet gevonden
mpif77.mpich: parancs nem található
mpif77.mpich: perintah tidak ditemukan
mpif77.mpich: príkaz nenájdený
mpif77.mpich: příkaz nenalezen
mpif77.mpich: команда не найдена
mpif77.mpich: командата не е открита
mpif77.mpich: 命令找不到
mpif77.mpich: コマンドが見つかりません