unable to re-intall windows no disk or start menu

Hi All

When i start up the computer all i get is the desktop picture, there is nothing on there, such as the start menu etc. I have had a look on the net and tried to see how to re-install xp (without a disk - as the computer never came with one (I have a the code for it on a sticker on the side of my computer)) and it tells me look in the I386 folder from my computer. However im unable to get to that folder as my computer just shows the background picture of blue skys and green hills.

Im not fused with having to install everything again as I have everything saved on an external hard drive and have all the install disks for any software on there.

Any help would be received kindly

thanks
Samantha
Advent 3412
xp home