I have updated Java, reinstalled the Twitch app, and I still can't get anything to load. Before it would give me an error message with the most recent launcher, now when I launch it uses the 1.6.91 launcher and doesn't load anything.
Fixed. I forgot to start a vanilla world in 1.12.2 and then load up the modpack I wanted.
So i believe i have stumbled across the fix to this problem, which i've been having forever, while trying to fix a completely different problem. I'm not 100% sure this is the fix but this is the only thing i've majorly changed since.
The java path is not set. The fix is fairly simple. Find your java folder. Should be some thing like "C:\Program Files\Java\"
Locate to the bin folder "C:\Program Files\Java\(will be different depending on your version of java)\bin" Then copy this directory address.
go to the windows search and type "advanced system settings" then press enter.
Under the advanced tab click "Environment Variables."
Under "system variables" locate Path and Double Click it.
Press "New" and paste the address from before. Press OK twice. and you should be good to go. make sure to restart curseforge
Again im unsure if this is the fix. but please let me know!