I dont know how, but some how someone hijacked it. I already contacted STEAM on Monday the 16th, but still no answer. I read somewhere that it is 3-5 days they contact you. But we'll see the outcome.
sorry to hear that man i have had an account hijacked before and it took them 3 days to get it back to me some times it can take them a little while but i hope you get your account back soon