cathytsir:
does that mean that the communication from the pc to the board through USB cable is ok?
Yes.
I guess now i have to try burning the bootloader.
Reburning the bootloader is the next step.
should i follow the official instructions from arduino site?
Which official instructions (post a link)?
if i perform it is there any chance i also destroy my second Arduino?
Anything is possible. But, I have used a "second Arduino" many times to burn bootloaders / burn Flash and my "second Arduino" still works perfectly. Adding some 1 k to 220 ohm resistors to the SPI connections should eliminate any possibility of damaging either Arduino.