Hi @dhavamani.munusamy
Type in the command "3DCONFIG" and check if its turned on. If its turned "off" then turn it "on" and see if that makes any difference. If this doesn't help then please post a screen recording of AutoCAD so that we can help you out 
--------------------------------------------------------------------------------------------------------------------------
ವಿನೋದ್ ಕೆ ಎಲ್( System Design Engineer)

Likes is much appreciated if the information I have shared is helpful to you and/or others.
Please mark "Accept as Solution" if my reply resolves the issue or answers your question, to help others in the community.
--------------------------------------------------------------------------------------------------------------------------