It happens when hibernate file gets corrupted. Try this:
Disable "Hibernate" from Power Options and restart your system. It'll delete "hiberfil.sys" file automatically. Now re-enable Hibernate option and you should be able to use hibernate in your system.
If it doesnt work, then again disable Hibernate and boot into Safe Mode. Enable "Show Hidden Files" option and disable "Hide Protected Files" option in "Folder Options". Now open C:\ drive and you should be able to see a file "hiberfil.sys". Delete it. Restart system, Re-enable Hibdernate.