Client not starting up

So Im not sure if this is the right place to do this but the client is not starting up. After looking it up on here I was only able to find outdated solutions. I have used the hextech repair tool multiple times and it hasn't worked. Ive also tried uninstalling and reinstalling and that has not worked either. when I double click on the Icon it will show up for about .5 seconds and then disappear and not start the program. Are there any up to date solutions?