unable to open wmv file attachments using windows mail

I have a new problem in that for the last three days I am unable to open wmv
files from my windows mail inbox. When I click the attachment, the prompt box
appears, asking me if want to open this file. I click yes and nothing
happens. This is new and just started three days ago. Prior to that, my
windows media player always opened after clicking the open tab in the prompt
box. Thanks very much in advance for any help on how to fix this issue.