Network problem cable plug.... Realtek Network Controller Not found. If deep sleep mode please plug the cable

I encounter a problem in lan outlet port when i plug the cable i doesn't work. Moreover, when i attempt to install the lan driver a massage pops up says " Realtek Network Controller Not found. If deep sleep mode please plug the cable " so the driver didn't finish installing and a I tried over and over but i doesn't work and pops the massage mentioned above.  and IT has been recommended to change Win to Win 7 home premium 64 bit but it doesn't work.Kindly let me know your answer.

thanx in advance.

It  is  DELL INS. 15  3537 core i5