@nishant, well i didn't play with atmega 8u2 even if it was so how come it burnt the code first time.these days laptops have only ports for VGA cable RS 232 port can be created by using usb to serial converter.As far as my laptop model is concerned i am using "Compaq presario CQ62".For using ICSP header one need to have avr programmer which i don't have.Now I am in very bad situation as i have to complete my project in less than 10 days and i don't have any other option available.Can you explain what can go wrong in burning a program(i burnt led blinking program given in example). i think there is some problem with reset. let me explain in details when i got my new bootloaded ic, after connecting it to board when i pressed reset button led connected to pin 13 blinked 3 times(which should). after that i burnt the program in atmega and led started blinking in interval of 1 sec. after that i tried to burn other program(avrisp) which resulted in error. now when i press reset button nothing happens. only previous prgram(led blinking) keeps on running.now can you suggest any thing??????