Volume Buttons have broken off

so i have been trying to tinker with my Walkman to make it work again. but the problem that i have is that the volume buttons aren't on my device anymore. I tried using aluminum foil to make it work but it works only when it wants to, so my question is, where can i get the buttons or if i cant, what can I do to make the volume button work properly or at least as close to proper as possible