Magento2 layout changed all of a sudden

Hello,

I am new to Magento. I am building a new eCommerce website for our company, which sells thousand of products. I have installed Magento2.1.12 via xampp yesterday and started configuring the site. After setting up Stores - Configuration - Web; Unsecure and secure links, the Magento admin panel and front end layouts have completely changed. It looks as if CSS is not working i.e. no styling both in admin panel and front end. Does anyone know what have I done wrong and how to retrieve the default settings back?

Here is a screenshot:

Attachment 12299




Thanks in advance!
-A