Thanks for your reply, I have installed windows live and when i go to craigslist and try to reply through windows live it says there has been an error,dont know why
Are you sure you installed Windows Mail or something else from the Windows Live Essentials package? You can just download Windows Mail at http://download.live.com/wlmail
if you didn't get it.
Otherwise, go to the Start Ribbon and select Default Programs. From there, select Associate a file type or protocol with a program
From there, scroll down to the PROTOCOLS section and set the MAILTO protocol to whatever email program you've installed.