Go to sync.opera.com in Opera for windows.
Login to your account using same username and password.
you will find an option to "reset passphrase" there.
When you reset passphrase, you won't loose any data from device.
Once you reset passphrase, try logging in to your device.

Go for it!

Open My Flow. In the left side pane of Opera, you'll see what looks like a Star Trek badge on its side.
Reveal the QR code. In the My Flow pane, click "Reveal the QR code."
Scan the QR code.
Connect your devices.
Configure what to sync.

Hope this helps.

If you're encountering an issue where images are being inverted from black to white in the Opera browser, it's likely due to a specific setting, extension, or rendering issue. Here are some steps you can take to address this problem:

Check Browser Extensions:

Disable any browser extensions that might be affecting the rendering of images.
Some extensions can have unexpected effects on website appearance. Try disabling extensions one by one to identify if any are causing the issue.
Browser Rendering Issues:

Check if the issue occurs on specific websites or across all websites. This can help determine if it's a global rendering issue or specific to certain pages.
Clear your browser cache and cookies to ensure that outdated or corrupted data is not affecting image rendering.

Opera Signing You Out:

Clear Cookies and Cache: Corrupted cookies or cache data can cause sign-out issues. Try clearing your browser's cookies and cache.

Check Extensions: Certain browser extensions might interfere with login sessions. Try disabling extensions one by one to identify if any are causing the problem.

Check Privacy Settings: Ensure that your browser's privacy settings are not set to automatically delete cookies or data upon closing the browser.

Browser Update: Ensure that you are using the latest version of the Opera browser. Updates often include bug fixes that could address sign-out issues.

Go to sync.opera.com in Opera for windows.
Login to your account using same username and password.
you will find an option to "reset passphrase" there.
When you reset passphrase, you won't loose any data from device.
Once you reset passphrase, try logging in to your device.

Go for it!