Hibernation is a power-saving state designed primarily for laptops. I was using it in windows xp a lot. Now in Windows 7 it's gone... And not so easy to fix this, without know how:
1. Open Command Prompt with Administrator rights. To open Command Prompt, type CMD in Start menu and then hit Ctrl + Shift + Enter to open the Command Prompt with Admin rights.
2. Next, type the below command and hit enter:
powercfg /hibernate on
This will enable Hybernate support in your Windows 7.
If you can’t see the Hibernate option in Start menu then do the following tasks:
1) Type Power Options in Start menu and hit enter.
2) In the left pane, open the link labeled “Change when the computer sleeps” and then open the link “Change advanced power settings”.
3) Under the Advanced Sleep options, expand the Sleep tree and turn off Hybrid Sleep.
4) Now go back to Start menu to see the new Hibernate entry.
I hope this helps,