Hi @geetha123456789 and welcome to our adorable Community 😊 The in-game events and challenges are not always available to everyone. They are sometimes a part of testing and the studio releases them only to a certain amount of players. You can read more about this on the link below.
Hi @geetha123456789, welcome to our community. To add to what @firebombmarkus wrote, I would like to take a moment to offer you a message
for all newbies to learn more about our community which you can find here.
We always run contests so be sure to do them for a chance to win gold bars.