blank league of legends client after logging in

helpp i don't do know what to do, as soon as i log in to my account my client goes blank. my friend says it doesn't even show me as online despite having told me that my log in was successful. i've tried deleting client files, uninstalling and installing again, changing my internet explorer settings, changing the properties of the league client, and restarting my computer like 5 times, nothing works D: