ovs-vsctl: 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/lib/debug/usr/bin/ovs-vsctl - from package: openvswitch-dbg
/usr/bin/ovs-vsctl - from package: openvswitch-switch

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