online exam project how to keep mainta previous page values

hello , i m working on a online exam project without database. all the question are written on page in label control while all answer are in radio button now problem is when a student answer all the question and go to the next page. and suddenly back to the previous page anll the radiobutton show unchecked and he/she don't know that what answer he/she given on that page , so can anybody help me to keep maintain all the value of previous page its very urgent