Need instructions to reset PRAM on OS Snow Leopard

My provider suddenly stopped recognizing my Mac while my Windows PC, laptop and Samsung tablet have access to wifi. Could not find the Command-Option-P*R solution given for the Snow Leopard OS, only Yosemite. In other words, my wifi router is working for all other devices but the Mac.

Provider suggested I change my email client to a Yahoo account and new password. That works fine but I prefer my Macmail client after having used it for many years.

Thanks for any advice.