On WhatsApp, unblocking someone does not automatically restore your previous chat history if you deleted it. However, if you never deleted the chat, the old messages will reappear as greyed-out placeholders. More critically, you will not see any messages they sent while blocked . The block is a complete information firewall.
If you're using Google Contacts, follow these steps to unblock someone on your contacts list: how to unblock someone on contacts
Some Android versions have a separate block list inside the Messages app and the Contacts app. If you still don’t receive texts after unblocking in the Phone app, open Messages → Settings → Blocked messages, and ensure they are removed there as well. The block is a complete information firewall
You can have a contact saved in your phone book but still be blocked on WhatsApp. Conversely, you can unblock a number on your phone but remain blocked within an app. The process is not universal; it is platform-specific. You can have a contact saved in your
Unblocking does not retroactively deliver missed messages or calls. The digital ether has swallowed them permanently. You are only opening the door for future communication.