my board works no more

ey!

I seriuosly believe I burnt some part of my arduino board. The fact is that when I connect it to the ide I have the led 13 and the "on" led working, but the ide sees no board.

is it dead? is there anything I could do?

I was working in the following project http://mrossphoto.com/wordpress32/neopixel-ws2812-dlw/ and I connected the arduino board to the 12 Volts power supply while it was still connected to the usb, and apparently it didnt like it. Moreover, after a few seconds, my computer also decided to turn off itself.

Which board exactly. Arduino R3 boards have electronic switch between USB and barrel jack, no problem should be to have connected both. Disconnect all and try to check power with multimeter first.

arduino mega 2560 r3

which power are you suggesting me to check?

thanks!

ow fuck. little detail I forgot to mention.

When this happened the regulator was missplaced. I solder it the other way around, so this for sure has something to do with the accident.

Ahaa! Try to check the power supply Vcc on onboard regulator etc. step by step.

I would love to. can you guide me a bit?

I wouldnt know how to do this.

the power supply work alright. I am using it right now

You have to provide more detailed information what you tried to check and something more about your mistake could help. Follow the schematics of the Arduino to check static voltages VCC on chips at first. There is 5V regulator also 3V3 regulator, fuse, comparator, etc. It can helps to find broken component. If everything is OK it is probably pointing to problem with small ATmega16U2 which is USB/RS232 convertor. It is able to connect it to programmer via ISP connector, but you have to have one, and check if 16u2 answers. It is not easy to provide an advice with poor information. I have no more ideas at now.