Are there any exclaimation marks next to your hardware listed in the device manager, network adapter area? Does your ethernet and/or wireless card show up there?
I did not find what I was looking for here but this link may be helpful to you anyway
http/www.samsung.com/us/support/owners/product/NP-NB30-JP02US
What I was looking for was a hardware connection which would explain your ethernet not working in conjunction with your wi/fi issues - I found nothing that would indicate that would occur together so I am inclined to believe your issues are software related - Windows being my primary suspect.
Personally, if there are no exclaimation marks next to your hardware in device manager, I would backup any data I wanted to keep and do a system restore including a BIOS update. Available somewhere within the link above (check your label and ensure it is the correct model first)
As far as getting inside of netbooks, that is a somewhat gray area as there are few "how-to's" about that (I could find nothing for your specific model). If you are inclined, and a system restore does not return functionality of your networking capabilities locating your wi/fi card should be fairly easy once opened - doesn't explain ethernet issues though.