Check your computer or mobile device as a starting point. These kinds of problems are frequently resolved by restarting your device or by closing and reopening your browser. If that still doesn't work, make sure that your device or browser doesn't need any updates.
Additionally, there is a chance that an older game you are playing is a Flash-only game. Since Flash is typically disabled by default in browsers and is not supported on mobile devices, the title may not be able to load.
But as time goes on, the majority of developers are either removing their Flash games or switching to HTML versions that are compatible with a wider range of gadgets. Your device should show a specific error message informing you that Flash support is the problem if it is.
After completing these steps of troubleshooting, if your problems have not been solved, get in touch with customer support.