in the attached circuit i use analog signal to drive buck converter by atmega8 and it was working well . i connected MCP617 on the same breadboard to measure current in the circuit using zero ohm resistor . supply for atmega8 and the op amp from lm7805 where the input for lm7805 is 12 volt which was used as supply for IR2112 . when i add the op amp circuit i forgot to connect the negative terminal of the load to pin 3(+ve input) of the op amp then i switched on the power supply or the battery .i couldn't even see any signal the driver got very hot and the op amp ,but the atmega 8 didn't get hot but there was no output from it. i don't know what happened ,why did i lose the three ICs

 

Always measure output from voltage regulators before connecting.
And use a LED, that will tell you abnormal voltages as well.

If you are paranoid, use a zener diode 5.6V and a fuse. No seriously, it costs money and takes efforts to replace chips.

 

the output of regulator is 5 v and it can't exceed this value .i will lost my mind what is the reason that burnt those chips all of them and which one burn the others . please if any thing is n't clear you may ask

 

Help me understand: The circuit above the red and green circled areas, everything other than the op-amp circuit, was working fine. You then added the op-amp circuit and did what?

I also did not understand your reference to a "zero ohm resistor".

 

the driver got very hot and the op amp ,but the atmega 8 didn't get hot but there was no output from it.
zero ohm resisitor (resistor in m ohm) .006 ohm

 

I should have used a question mark:
The circuit above the red and green circled areas, everything other than the op-amp circuit, was working fine?
Please be precise about what was working, and then what you did that caused the problem. Reference your drawing. I still cannot follow your words.

A photo of your build might also help. It is very easy to make wiring mistakes or to get a pinout wrong.