Motherboard cannot detect ethernet cable !

[bobleeswagger666]

Hi i am using an asrock z77 pro4 motherboard and it is not recognizing the ethernet cable ! even when the modem is on the computer shows no internet connection ! all the wires are correctly plugged in and the latest ethernet driver is also installed ! i have had this problem before but it went away on its own last time, and now it is troubling me again(it should not happen )
please help me as i cannot do any work without internet on my pc

 

[mouse24]

Are you sure you are using a regular ethernet cable and not a crossover cable?

 

[bobleeswagger666]

now my internet is working fine :/ but this problem keeps occuring !! it pisses me off and this problem usually occurs when i switch on the modem after switching the cpu on (50% chances of not detecting the ethernet cable) .... if i switch on the modem before the cpu is switched on it works fine !
wtf is this it shld not happen like this
and yes i am using the normal regular ethernet cable