Can you right click the desktop? If so, choose arrange icons by, and select show desktop.
Another thing you can try is to boot, open taskmanager and kill explorer.exe
Then open task manager again, and click file new task, run, and type explorer.exe
If that brings back your icons problem solved.
If not, you can try booting to the PC, open task manager, click file, new task run, and then type:
Make sure you have the XP cd available because it will ask you to insert it.
That should fix any files that might be screwed up and repalces them with new files from the CD.
Are you using any themes or anything like that? If so disable them... and see if that works.
If you are using stardock, window blinds or something like that... remove those programs.
ALso, if you can, try running in safe mode and doing an antivirus scan... see if anything is picked up by your scanner... if so take the appropriate steps to remove it (sometimes viruses can make icons disappear).
TweakUI for XP has a setting to allow you to rebuild the icons if there is a problem for some strange reason:
Download and install that.
Have you installed any hardware, drivers, software etc... recently? As in right before the icons disappeared? If so, remove them... and reboot.
ANd finally, try to open task manager, and click file, new task run, and type:
CHoose to do a diagnostic startup. and reboot.
Then if everything works, go back into msconfig, and under startup, start adding those items that are unchecked one by one. And reboot. IF you add an item and it causes your icons to disappear then you've sorted the problem and can remove that item permanently.