Why I can only use wow in windowed mode?

I've had this problem for a while now, the only fix that I've found is to delete the client and redownload it. The thing is, when i enter in settings and i disable windowed mode so I can have wow full screen it just minimizes itself in the taskbar and no matter how many times i click it or close and reopen the exe it just stays in the taskbar and refuses to open. Prior to a few days ago the exe worked just fine. The problem persists even if i redownload the entire client. If any of you have encountered this problem please tell me what's going on.

First, you need to make sure your gpu drivers are properly installed.
Second, whenever you download a wow client, make sure you go to the client's folder properties and make sure to uncheck read-only.

Beyond this, what is your current resolution? What settings exactly are you trying to run in the wow client when you're experiencing the problem?