My messenger doesnt work

Hello,
I had the messenger 2009 and it was the best i ever tried.
Then one day out of no where it stopped working i could get on and sign in and talk to one of my friends for like 5 min. and after that it would get like stuck so i download a another one but it said that i already had one so i deleted it .Now i have tried to download one for the last 3 days and every one i download it doesn't work. It completes the download but i cant find it or i can find it and it doesn't work.I don't know what to do i bet that i have tried 20 times. So please can someone help me.