Hard drive went from 400gb to 40gb

Hi friend,
I need a help few days ago everything was working working fine. After coming from my Business Tour I switch on my pc and when I saw my drive (Drive C:\) instead of showing 400gb it only should me 40gb.

Following are my pc Configuration.

Intel Core 2 Duo 2.6 GHz.
2 GB RAM.
400 GB HDD.
Nvidiva 9600 GT.

Sure i can help you with that may i know which operating sytem are you using ?

I am using Windows Vista

Windows Vista can fix this problem you need to follow few of the steps:-

1. Right click COMPUTER on the desk top.
   
2. Click MANAGE.
   
3. Click DISK MANAGEMENT.
4. Right click disk 0 (your c: drive).
5. Select Extend Volume and follow the instructions.

That should extend the C partition so it may uses all the uses.

Thanks a lot i am anle to see my full 400gb now thanks a lot......