Hi Esther, first, would you please disable HTML-mails in your mail client?
Now to your problem. The thing you're looking for is called APM or ACPI. As these are very large topics, best would be that you tell us exactly what you did before hibernation stopped working (perhaps you updated your system and installed a new kernel?) and - of course - find out which of these two you used for it.
Bye. Thorsten
