Hello Bruce,
If your Authenticator app is no longer generating valid codes, reinstalling alone won’t fix it because the app doesn’t store the secrets locally in a way that survives removal. Each account you add to Authenticator relies on a unique secret key that must be re‑provisioned from the service requiring authentication. When you delete and reinstall the app, those keys are lost, which is why you can’t get codes anymore.
The only way to restore functionality is to re‑register the Authenticator app with each service. For Microsoft accounts, you need to sign in at https://mysignins.microsoft.com, go to Security info, and add the Authenticator app again. This will generate a new QR code or setup key that you scan with the app. For third‑party services, you must log into their security portal and re‑enable two‑factor authentication, again scanning the new QR code into Authenticator. Without this step, the app has nothing to generate codes from.
If you are locked out of an account because you cannot generate codes, you’ll need to use the recovery options provided by that service — usually backup codes, SMS, or email verification. If those are unavailable, you must contact the service’s support team to reset your two‑factor authentication. Microsoft support can reset MFA for your Microsoft account if you cannot access backup methods, but this requires identity verification.
In short, deleting and reinstalling Authenticator wipes the stored keys. You must re‑provision the app with fresh QR codes from each service’s security settings. Once you do that, the codes will work again.
I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!
Domic Vo.