Signature_not_varifiable on iPhone 8

[rkcprimal]

I started a NEM wallet on my previous iPhone 7. (I believe I have an iTunes backup of this phone). The NEM wallet on the new phone seemed to work fine. My first NEM coins were transferred into the original wallet on May 25, 2017. The last coins were transferred in December 6, 2017. Everything worked perfectly. I wanted to transfer some coins to an exchange and got the Signature_not_varifiable message.
I had converted my log-in from passphrase to Touch ID. I switched the log in back to passphrase on the NEM wallet. Now the wallet will not recognize my passphrase which I had recorded and I know it is correct. The IOS wallet just shuts down after I enter my passphrase.
I can see my coins on the blockchain associated with my address, but I don’t know how to gain control of them with the IOS app. I have never experienced such an issue before. Is there a solution to my problem?

Thank you all so much for your help

[CryptoBeliever]

So when you restore from backup your private was no longer there… Description provided by @thomasoehri here:

Dear administrators. I appeal to you!

Yes that is correct. You need to have a backup of your private key, either written down or stored as a backup QR code to regain access to your account. When the private key is missing there is no way to send transactions from that account. And nobody is able to help regaining access. Only the person that is in possession of the private key for an account is able to proof that they own the account. There is nobody that can reset the password, or in this case the private key for your account, like…

Do you have old phone, private key or qr code with your private key stored somewhere?