I got a new phone and tried to snyc my Jaxx Wallet with my old phone, because they were both Samsung S5's I downloaded the Jaxx wallet on my new phone and tried to sync it with the old one, the problem is somehow i synced the wallet that had $0 in it over the one that had my funds in it. It gave me the warning about make sure you have your 12 word key so I wrote it down but realised it was the key for the new wallet and I don't have the key for the old wallet. Is there absolutely anyway to get back to my old wallet, I wish it was easy as deleting or undoing what I had done to uncover my old wallet. I know most say it is impossible but I have heard of people recovering lost coins and I fell because I still have the device the wallet was on surely there is someway to access it.
Without the 12 word phrase, there is no way to recover your coins. So you must do everything you can to try to recover those 12 words.
It sounds like your new phone created a new wallet upon startup, so the 12 word phrase will not be recoverable from there: you'll need to work with your old phone.
If the old wallet file is still on your old phone, then its no problem. Just open up the settings, and copy the phrase from there.
If the old wallet file was overwritten on your old phone, then you'll want to explore options to 'revert to a previous state', if you have a cloud backup service enabled this may be possible. If no option exists like this, you could explore professional data recovery options, but these will likely be expensive.
Best of luck