Something wrong with the board?

I know that the software isn't malfunctioning, and that my board won't light on when I try to run a program. I tried restarting the board, with no luck. I also tried restarting my computer, also with no luck. Help!

More information please.
Board,revision of the board,the version of software you are using.
You get any errors while uploading sketch to the board?

Hello,

I´m very new in this.
I have problemas with the conection between board and computer. I tried to connect the board to different computers and none of them reconigze the board in the serial port. Arduino uno. I tried in macs and pc. Yesterday was working but it gets by mistake a shot of 12V while using a relay.
Now also It gets a little more warm than before. The green light still work, but not a led between 13 and GND.
Did I burn it? anything I can do to see where is the problem?
Thanks in advance

Little shot of 12V - that'll kill it.