Thanks all , the problem is solved !
I found that the problem was from the voltage supply ,although I am using 5v regulator to supply the microcontroller but the microcontroller was unable to function with it, I don’t know why is this but maybe the voltage regulator is of bad quality !!
I tried to supply it with a 5v from 5v of the Arduino UNO board and the 8051 led blinking circuit worked well 
, this is how I detected where is the problem.
but now I am facing another problem ,the LCD in my circuit is not working !!.
when I tried the LCD code and circuit with ISIS proteus simulation it was working fine ,but when implementing it on my breadboard it doesn’t work ……. !!!!!!!!!!!! this would drive me crazy !!.