Hi there! I understand you're having trouble signing into the Smart Closet app via Google, and you mentioned your data is gone—let's work through this together.

Just to get a clearer picture:
- Are you seeing the "Authentication failed" message immediately after entering your Google credentials?
- Have you been able to sign in successfully before on this device?
- Did anything change recently with your phone or account, like a system update, app reinstall, or Google account settings change?

Meanwhile, here are some initial steps that often help resolve Google sign-in authentication issues on Android 10 using WebKit-based apps:

1. Check your internet connection — Ensure your device is connected to a stable Wi-Fi or mobile data network.

2. Clear the Smart Closet app cache:
- Go to your phone’s Settings > Apps & notifications > Smart Closet > Storage > Clear Cache.

3. Force stop and restart the app, then try signing in again.

4. Check Google account permissions for Smart Closet:
- On your desktop or mobile browser, go to your Google Account settings at myaccount.google.com/security.
- Scroll down to Third-party apps with account access and make sure Smart Closet has permission. If not, grant access or remove and re-add it.

5. Try signing in on a different device or browser to determine if the issue is device-related.

If you've already tried any of these, please let me know, and we can try more advanced troubleshooting like re-syncing your Google account on the phone, checking device admin settings, or analyzing app data restoration possibilities.

Does this make sense so far? Have you tried any of these steps already?