My computer is not giving me standby or hibernate option when i want to shut it down. It is before i formatted it but after I only have the option of restarting or turning it off. What could be the cause of this?

Since you say it was there before you re-formatted you system, that means your system does support ACPI management.

Try this:
1- Go to "Control Panel -> Power Options"
2- Click the Hibernate [/b]tab, select the[b] Enable hibernate check box, and then click Apply
3- Though strange that the Stand-by option does not show up, but doing the above would put both "Stand-by" and "Hibernation" options on the shutdown menu.

If only the "Stand-by" option shows up, simply hold down on the "shift" key and it would change to "hibernate".

Hope this helps!

if your VGA drivers are not installed u won't be able to carry out the steps outlined by maleeq,
so make sure your vga drivers are installed before u can think of enabling hibernate from your power options.

maleeq and sawyerrken have both said it all.

@ sawyerkken, maleeq and inze, Thanks to you all