How much memory have you allocated your Hortonworks Sandbox? You will need at least 14 GB and must have enabled virtualization in your bios Enable Intel Virtualization Technology (also known as Intel VT) or AMD-V depending on the brand of the processor.
Hey @Harish Kumar, sometimes VirtualBox does not display the final screen of the sequence. Could you try firing up your browser and navigating to http://localhost.com:8888 ? Does the sandbox splash page come up?
If not, try giving it some time. If you're short on RAM, it may take a while for all the services to come up. We recommend at least 8GB for the HDP sandbox.