Question about Outlook Express

I had all windows live which includes messenger ,one day it  just disapeared,I tried to download it again and it says I already have the lastest messenger  installed,if so, I cannot find it.I click on start menu and type windows messenger but it does not show up,I also went in programs to see if it's installed and it's not there so what do I do? I want windows messenger  back,Ok I'm using windows 7,OS,HP Touchsmart All-In-One computer 64.my hotmail account I usually got through messenger i would click on inbox,any and all help would be appreciated...                                   Thanking you in advance                                         pennyjo