So, I'm not sure if Jaxx already fixed that, but there was an vulnerability which let you get your backup seed from the wallet files. And since they didn't care about it, maybe it still works.
Can you backup your Jaxx folder and try this?
https://vxlabs.com/2017/06/10/extracting-the-jaxx-12-word-wallet-backup-phrase/#demonstrationOr just try what I said above as it won't risk your current wallet anyways (you are just copying the folder and pasting it in another device, where Jaxx works).
The problem also is, I'm not really good with stuff like this. Have no clue to "backup a wallet" anyway.
All I usually do when installing a wallet on my PC is write down the seed phrase on paper. But in this particular case I forgot this.
Can you please read my previous post and answer on that?