The Prophet Muhammad (pbuh) is dead, there is no doubt about that. He also has a special status, which means when we say our salaam, the angels convey it to him. It doesn’t mean that we should pray to him or ask him for help, because even if you don’t believe him to be All-powerful you are still praying to someone in a similar fashion to praying to Allah. Why would you want to risk shirk, it is the only unforgiveable sin. The people who visit mazars in Pakistan follow a similar logic. Praying only to Allah avoids all this confusion.