Older messages in my WhatsApp are deleting automatically Older messages in my WhatsApp are deleting automatically. I'm not deleting them. I thought maybe someone is using my WhatsApp account, so I deleted my account 3 times, but still the same thing is happening. Can anyone tell me what's happening with my WhatsApp, and how to fix it?
How exactly is the deletion happening? WhatsApp has an option wherein the sender can unsend (or delete) a message he has sent within a limited period of time. So, if you are referring to that, then it is a WhatsApp feature.

However, if even your own messages are getting deleted, then it is something else.WhatsApp does not have any option to automatically delete the older messages. So, we can rule out the fact that it is happening automatically. 

Next, it is possible that someone else has access to your WhatsApp messages via WhatsApp Web. You should check the WhatsApp Web option on your phone and ensure that there are no authorized devices which you do not know. If you do not know what WhatsApp Web is, then you should not have any connected computers on your WhatsApp Web.