Edit 2: So I just found the solution (at least for this situation,) I reinstalled the twitch launcher and it started working again and all of my downloaded modpacks remained intact as well as all of the saves on them.
I'm experiencing a very similar issue with the Twitch launcher, but first some backstory for what lead up to this: I was playing a modpack from the twitch launcher and went afk to deal with something IRL, I had the game on the escape menu to keep it paused. Partway through my task, the power went out.
Now, when I press play on any of my modpacks in the launcher it gives me the message "Java must be installed to launch Minecraft with the current launch method."
Edit: after I turned my computer back on I checked java and updated it