Simple internet problem is driving me CRAZY!

Hi all. I am out of the country and I have limited internet access in my hotel room. I used the internet for an entire week using a cable from the wall to my ethernet port. Two days ago my mac stopped letting me access internet pages, even though I am definitely connected to the internet. There is a problem with my network settings but I cannot figure it out! I don't know much about configurations and all that. I have never had this problem before.

I am sure this question has been answered before, but please point me to another thread or give some pointers. Thank you.

 

It looks like everything is on automatic. Can it get switched from one day to the next without touching anything?