Do you mean it disappeared from the start menu area? If so, right click in that area, select Properties and then Customize and make sure that the box next to 'My Documents" is highlighted....
My Documents doesn't show up in My Computer view on my XP PC? I don't know if it ever did and it doesn't bother me that it's missing. Shared Documents doesn't show up either but I got ride of that one on purpose.
http://www.tweakxp.com/article36827.aspx
My Documents folder missing in My Computer
This is a strange bug in Windows XP Pro but it can and does happen to everyone. When you open the My Computer screen and your Documents folder is missing but all the other users folders are there try this tweak.
STEP 1:
START > RUN > REGEDIT >
HKEY_LOCAL_MACHINE / Software / Microsoft / Windows / Current Version / Explorer / DocFolderPaths
Once you click the DocFolderPaths folder you should see all the user's folders.
STEP 2:
Add a new string value
Value Name: your user name
Value Data: the path to your docs folder ( ex. C:\Documents and Settings\your docs folder )
Exit Registry editor and open my computer, your docs folder should now be visable.
I know what happened now, when I installed windows it told me I couldn't have the username match the computer name, so after I installed windows I used control userpasswords2 to change my user name.