@Retailpiu
If I read the user manual for the TL-WR802N correctly, then a factory reset puts it into "Wireless Router" mode with the sole Ethernet port becoming a WAN port and it also switches Remote Management off (default setting).
That means you can't get into the TL-WR802N via the WAN Ethernet port and without knowing the default wireless password you can't get in via wireless either. There is no third way to get into the router.
It's a long shot, but the only thing you could try is to contact your local TP-Link support and ask if they can get you the default wireless password for the TL-WR802N with the MAC address(es) and/or serial number you tell them.
In case none of that information is readable anymore, then you can get hold of the MAC addresses of your TL-WR802N via the following methods:
The WAN port MAC address can be obtained by connecting it to a LAN port of another router and then check within that router's client list.
The wireless MAC address can be found by using some Wi-Fi Analyzer/Scanner software.