UI changed ERPnext GUI change?

Why am i getting this UI? has there been an update in the system !

please let me know i am unable to know if there are errors in my installation or there has been a gui change.

Yes, a new UI has recently been merged into the develop branch. Check out this thread for more info:

Version 12 will not be getting the new UI, so if you like the old one better you can continue using v12.