If no result, you can call AppleCare & they will arrange to have your computer shipped in for service. If your computer is no longer covered by AppleCare or you did not purchase such, you will have to pay for the call.
Thank you gents for the suggestions. I took it to a store (i watch) that is the only one near me. I was promised to have it checked, but still in doubts they are qualified enough to deal with it.
I think the problem happend when I did something silly by plugging a USB end and a connector at the other end wired to a digital receiver to flush that machine. I made that wire my self but had a problem figuring the colors of the 4 wire connections. It seems that the USB shorten something in the MacBook.
Hope that is not bad.