I blocked a contact and reported it on WhatsApp. I just found out that the messages have been deleted ....it marked as spam messages .. How do I get back those messages?
As soon as you spam a message in WhatsApp it fully deletes from your phone. If there was any media you might be able to access it from your file browser.
In most cases you will not be able to get back messages that were deleted because you marked someone as spam on WhatsApp.
You can however still try the steps outlined in this guide and see if you are able to recover the deleted messages - http://www.makeuseof.com/tag/accidentally-deleted-whatsapp-chat-history-heres-get-back/