Launcher fails to update

So I was having Java crash on me and I found a video that said uninstall completely and reinstall Minecraft on to your computer again I did that. As I re-downloaded it and it went to open the launcher it wouldn't update. Now Minecraft won't open. I tried repairing with what Minecraft provides it it doesn't work. I tried re-downloading it with a new download it won't work. Minecraft has not worked for me since the new Java update last Friday. It resulted in one of my worlds getting corrupt. Please help me.