i am sorry to say but there is little that can be done you will ahve to reinstall your xp sadly, i may be wrong and someoen knows a fix but to my knowledge there is only one and that is to reinstall it
there is one way but it costs money but it will give you a free trial the thing with the free trial is it will only give you the first 3 characters of your lost password but that may be enough for you

to jog your memory.
HERE IT IS download and use the free trial maybe 3 characters is enough for you to remember if not you will ahve to buy the full one
just looked at thast site again myself i am not sure if that one is for admin log on password retrieval it may just be for other passwords in the OS like outlook email and such.
there is
THIS ONE but it is like $70 to buy but does work it is a bit of messing about but if yuou cannot afford to lose the data on xp by reinstalling then you have to do this