So recently my younger brother had his right hand broken and currently can't play because he cant use his mouse as he can only use his index finger. I've been trying to figure out a way to make it so he can play but the game won't let me adjust the mouse buttons. If anyone can help please do. Thanks in advance.
Just tell him to play 
, that way he can control the mouse with his good hand and mash his face on the keyboard.
I thought you could rebind every action in the game, or what's the issue?
That being said, not sure if he should be playing with his broken hand!
I'm confused, what's the problem? You only need to click the right mouse button for most of the game.
Quick Cast = Reduce the number of clicks you need to shoot spells. CTRL + Q/W/E/R = upgrade that spell (way faster than trying to click on the upgrade icon mid fight).
The only things I could find right off that needed a left mouse click were the Pings, which while slightly problematic, aren't going to completely ruin you.
you only REALLY need the right mouse button to play
though honestly I would recommend he put as little strain on his hand as possible while it heals.
you actually can't rebind left click, theoretically you could but you'd have to go into the game files and change it manually which is against riot's rules of conduct (they consider it a competitive advantage to go in and change things at the games base level like that) so you can't do it. he might have to get used to just using one finger to right click :/
Update: Riot sent him an e-mail saying he may have to use third-party software and then gave him a list of rules on how certain third-party softwares dont work. Any suggestions?
The only solution I have is to buy a Tartarus
It's left handed and has a bunch of cool keybinding things, but not sure if you really need to drop 60+ bucks on a temporary issue...
I would suggest trying to get a game-pad with numerous buttons (i.e. 12 to 20) and an integrated mouse such that you can access all of them using a single hand simultaneously. I know that they make them for gaming (and other functions), but I forget their actual name.
You may be able to find it if you either search for it or ask someone more informed than I am.
You should be able to bind the buttons on the game-pad to your relevant keys (QWERDF, Space, Tab, etc.).
I don't think the game lets you adjust mouse-buttons through the interface, but you may be able to do so by editing the PersistedSettings.json file. It's not exactly the same thing, but you can get a rough idea of how to do so here:
