Do you use Opera Sync? If so, are you encrypting your data with a custom passphrase? Do you user Opera's VPN? Are you blocking 3rd party cookies? Have you cleared all cookies for google.com? Have you tried disabling all your extensions? Are you using Opera's adblocker? If you download the Opera installer, launch it, click "options", set "install path" to a folder on your desktop, set "install for" to "standalone installation", uncheck any checkboxes, you want and install (do not enable sync or anything in it), how does that Opera behave (right now at least)?

Nice. But kinda strange that it didn't work with Opera portable.

You can't restore your password, you can just create a new one. And data encrypted using the old password will need it to be decrypted.

Password sync is now available in Opera for Android 47 beta.