As far as I know, its not possible to recover them anymore, to be more sure you should probably wait for a staff member to view the forum or contact them directly
Recover accidentally deleted messages

Try Help and Support
This topic is from almost 6 years ago....
That said, once deleted, they're gone.

So you cannot recover them?
No.
I wish I could recover them. Mine ones are very important.

i deleted all the messages accidentally i request to recover them...please
You can't.
My child accidentally deleted all my messages (inbox), is there a way I can restore at least last month's?