Hard Disk Shows size smaller than its original

[meking]

Hi, every body
i would like if anybody could help me my 80 GB hard disk shows only 32 GB and i dont know what to do and it shows a message on the the mother board the message says S.M.A.R.T hard disk back up and replace i dont know what to do please could any one help me!

[Arup]

Its probably going bad, download the HDD utility from your hdd manufactuer's site and follow the instructions to test it out.