Hello, Vishnu
As was mentioned the issue is the memory limit on your server. You do not need to have any dev knowledge to contact your hosting provider and ask them to fix the limit problem. Once it will be done we will be able to assist you in solving any other errors.
If you are not satisfied using our theme you can submit a refund request here – https://themeforest.net/refund_requests/new
Kind Regards,
8theme team