There are several reasons why the game may not load Clash of Clans, and if you want to know the solutions to these errors then you have to see this…
The most common reason why Clash of Clans does not load on your mobile phone is problems with your internet connection, and in that sense you should check your mobile data connection, your Wi-Fi network to rule out or solve any errors.
Another reason could be that the app has a bug and you need to delete it from your device and download again. This is very common as sometimes files are downloaded with defects.
This video explains in a more illustrated way the frequent errors and their solutions: