lost files after update

Yesterday, I did a windows update for vista. When I restarted the computer it had lost my desk top and files, it had reverted back to an older desk top and files. I don't have my files backed up, LESSON LEARNED.
I think the files and most recent desktop must be in there someplace because the trash still has some recent stuff that I deleted.
Can anybody out there help, please.

That happened to me once on XP. It turns out that it switched my two hard drives (D and C), moving all of the data from C into D and vice versa. Do you have two hard drives, or a partitioned drive?