My partition disappeared

I have 2 external drives.
One is 1tb ( western digital )
The other is 320gb

They were plugged into my old laptop which had xp sp3 , but i got a new base system with windows 8.
The day after I got it , it wasn't showing the 320 GB drive , but i shutdown , switched it off at the wall and it came back into view on next startup.

I had a partition. I cant remember what drive it was on , but its disappeared. I had a lot of ebooks , manuals and photos stored on it , but when i open "computer" , its just not there , even after shutting down , turning off at the wall and rebooting.

Still very new to windows 8 , so im hoping its something as simple as "view" settings , which I have checked , but maybe missed something ?

Can anyone help me locate my missing partition ?

Thanks !