My error deleting an auto discovered device

I ignored (for my wrong) an auto discovered device. Now i cannot have anymore back the answer to add that device. I tried also adding manually that device but with no success. Home Assistant auto discovery doesn’t find anymore that device. How to add it again ?

Visit Settings/Devices&Services and select the Integration for your device. If the integration isn’t showing, add it. Then use the Integration to add the device manually.

Ok i try to be more clear. The integration is Meross LAN and i added automatically 2 smart plug and for error ignored the third smart plug discovered. I used the same integration to add manually the third smart plug but the integration doesn’t find anymore that device. In the meross app it is regularly added. How to add it inside Home Assistant?

Same for me. You have to edit core.config_entries in config/.storage.
First of all find the portion tha identifies your device (you can search by name or type) and delete it entirely.
You will find tag “source” as “ignore”.
Then restart HA, switch on the device, then it will reappear in your list.
I’m using “Meross lan” integration.