Vanguard is Riot's anti-cheat software, and it disables touchscreens. If you want to use your touchscreen, you have to disable it and then restart your touchscreen driver. I do, however generally want it to re-enable itself on restart, so I use this:
' stop_vanguard.vbs
' Stops Vanguard
Call CreateObject("Shell.Application").ShellExecute("cmd.exe", "/c ""net stop vgc & net stop vgk & taskkill /IM vgtray.exe""", "", "runas")
Based on this:
https://gist.github.com/AndrewMast/742ac7e07c37096017e907b0fd8ec7bb#file-disable_vanguard_stop-vbs