What Causes Short Term Memory Loss?

hi dr.... well, just wanted to ask that i'm having problem in recognising people. if i met them for the first time, i couldn't recognise them again in second time or third time. i got to see them frequently then it will stays in my mind. same goes to their name too. btw, phones numbers and road direction i couldn't recognise. my friends could tell it easily but for me it will be new. so is it comman or a disorder?