Have you tried:
1. Running as Admin? (Right-click the .exe and hit run as admin)
2. Temporarily disabling your firewall
3. Disabling Discord, Vent, TS, TV, pretty much anything that has the potential to take priority over the launcher, including web filters.
4. Basically on the last point, making sure you don't have a virus, e.g. run a decent virus scan(I recommend Malwarebytes) to make sure.
5. If you run out of other ideas, you can always double check to make sure your account isn't bugged(Never heard of it happening, but I'm new here myself) by creating another account and trying to log into that. It doesn't seem likely, but if you've tried the other stuff, it might be worth a shot.
If that doesn't work, I can see if I can find some other things to try.
Matt