How to find deleated facebook messgs ongmail

Hello,
Last week i was finally able to find 2 needed old messages from Decemebr 23, 2009... sent from facebook to my gmail account... but when i went to retrieve the messages the next day they were gone and nowhere to be found...

I had gone to my gmail trash to locate the two messages succesfully... but after reading them it seems that they were not saved in my gmail inbox as - example - Mary has sent you a message on Facbook...

Please let me know what can be done or what i need to do to recover these two needed messages.

I need these two messages badly.

I thank you in advance,

Steve