Please Help Install Bug issue

Hi guys, this morning i was downloading the patch that had occured today and my computer blue screened and restarted. When i restarted my PC I went to continue to download the patch, but i found out that league wasnt anywhere to be found. I googled this problem and have had no answers or slight tips on how to fix this issue, it was no were to be found in the control panel, I deleted everything in my computer involving league of legends and it still wont let me download the game now, it gives me this error

"Another version of this product is already installed, installation of this version can not continue, to configure or remove the existing version of this product use add/remove programs on the control panel" I dont understand how im supposed to do this if i cant even find a single league file, Please help out guys