Bitcoin investment unable to withdraw

Ive invested money into bitcoin about three to 4 years ago. One day somebody phoned me and said he is from America, if I dont withdraw my money in the next three days he said im going to loose it! At that stage I was in between moves from provinces and couldnt find my padswords. I eventually found it after some of my furniture recently came out of storage. How on earth can you loose your money if it is a legal investing business and I need assistance from a bitcoin consultant to withdraw my investment and I cannot gel hold of anybody, google keep on regerring me to another site. Pls pls see if you can assist. Greetings