If it is not showing any partitioning the partition table is probable wiped out. You would need to create the partition table "exactly" as it was before. I don't think you have lost any data yet. I have never done this so I can't confirm that this will work so you might want to get a second opinion.
You probably made this one big partition run fdisk /dev/hda.
Command (m for help): n
p primary partition (1-4)
Partition number (1-4):1
First cylinder (1-10, default 1):<return>
Last cylinder or +size or +sizeM or +sizeK (1-10, default 10):<return>
Using default value 10
Command (m for help):t
Selected partition 1
Hex code (type L to list codes):c
Changed system type of partition 1 to c (Win95 FAT32 (LBA))
Command (m for help)
Disk test: 0 MB, 0 bytes
255 heads, 63 sectors/track, 10 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
test1 1 10 80293+ c Win95 FAT32 (LBA)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
You numbers will differ than mine. I have actually tries to restore a lost partition table using fdisk. I don't think you will lose any data, but you shound definatly get a second opinion.
Let me know how it goes.