Can't re-download League

So after the update where Bard came out, i updated the client and after i hit the "launch" button nothing would happen...sometimes i've waited for hours and still nothing. So i decided to uninstall the Riot games inc. and League all together from my pc. All was well until i go to re-download LoL. I came to the main page www.leagueoflegends.com and selected "download the game" then after i select to run the program an error box pops up that says "Another version of this product is already installed. Installation of this version cannot continue. To configure or remove the existing version of this product, use Add/Remove Programs on the Control Panel." and it's been doing this for the past week or so now...I'm out of ideas..