ovs-vswitchd: 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/lib/debug/usr/sbin/ovs-vswitchd - from package: openvswitch-dbg
/usr/sbin/ovs-vswitchd - from package: openvswitch-switch

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

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