Help with statistics - detemining mean and sd with no raw data list (Jan/02/2011 )

hi there. I hope you can assist me. I need to figure out how to determine the means and /or sd from other data that is given instead of list ofraw data. More papers publish medians, maximum and minimum values, quartiles, etc. Even to determine the standard deviation of either the mean or median, formulas require the user knowing the raw data. But how can you figure out the mean value of a set of data when you know sample number, median and the maximum and minimum values from that data set?
e.g. n=21, median=24, mim-max=17-28

thank you inadvance for your help

You can't - you need the raw data for that. If the data is normally distributed then medain = mean.