All of my files locations have been renamed / changed

Hi,

Got a big problem.

For some reason iTunes has very annoyingly move all of my Mp3 files in
Windows explorer into different locations. Before the movement all my files
were stored in one single folder name as the Artist name - Album name like
below and then the songs were listed:

Artist Album name
2Pac - Greatest Hits CD 1
Oasis - Familiar To Millions

But now all the songs are located in 2 folders, first it has a list of all
artists, you click on that folder then it has a list of albums for that
artist then when you click that, the songs then appear.

Does anyone know how to get it back to it's orginal state. For eg, by maybe
using the tag info to rename all of the folders.

Thanks. VERY MUCH APPRECIATED IN ADVANCE

Gav