Low or no connectivity?

I am using a Dell pc and have it connected using a wireless dongle which connects to the internet perfectly, however i have tried connecting to the internet with an ethernet cable using an ethernet plug TP LINK 200 MBPS, however when its connected it says it has Limited or no connectivity, I have reset the modem, and various other things which i found on the internet to do and have now run out of ideas of what to do??