I have a 2003 bmw 330ci i recently just went to Ensenada B.C it had no problems getting there everything was find until the next day when i turn it on it turn on fine like a normal car but once i got to my cuzins house i turn it off and went and knocked at my cuzins well he wasnt home so a minute later i got back in the car everything turn on like if it was going to turn on but when i crank the key nothing happens the engine doesnt turn or anything. Really weird cause everything works fine and that happen just in a matter of couple minutes. I have been thinking i might of desprogram the key becasue i was hitting it against my cuzins cell door trying to knock with my key really hard. Am wondering what the problem could be? now i need to find a way to tow it to the border for bmw to pick it up. I was wondering what the problem could be?

Could be the key, but BMW has some good repair shops in Mexico. Check the yellow pages. AS they will need to run some tests to be sure.