Dear my brother Mike, Thank you thank you thnk you....It worked. My mistake is in mclr pin. I had connected it to ground. When I changed it to +5 V, it worked...Thank you very much
Yes, you can see it in the pictures. Pin 1 (MCLR) is connected to ground through a 10K resistor, just like the rest of the unused pins. On the 16F877 you cannot disable the external MCLR so you have to have it pulled up, not down.
Too bad such a seemingly small mistake caused so much grief, but in the digital world every little thing is important.