Hi there! I’m Daniel, happy to help get your Mahjong app working again. To start, could you tell me a bit more about what exactly is happening? For example:

- Does the app fail to open, crash, freeze, or show an error message?
- When did the problem start?
- Have you recently updated Windows or the Mahjong app?
- Have you tried any fixes so far?

Once I have a clearer picture, I can guide you through some steps.

Meanwhile, a common and simple fix on Windows is to try resetting the app. Here’s how you can do it on your Windows 10 system:

1. Press the Windows key + I to open Settings.
2. Click on “Apps,” then “Apps & features.”
3. Scroll to find “Microsoft Mahjong.” (If you also have "Microsoft Solitaire Collection," you could try this with that app too.)
4. Click on it, then click “Advanced options.”
5. Scroll down and click the “Reset” button. This will clear the app’s cache and data and might resolve the issue.
6. Try reopening the app after resetting.

If resetting doesn’t help, next steps include checking for Windows updates, ensuring your graphics drivers are current, and possibly reinstalling the app.

Let me know what you experience with these steps or if you want me to guide you through more advanced troubleshooting!