For this kind of request you need to open a request directly with firemonkeys. Community can't help you because none of us deal with accounts
That said there might be 2 reasons why this could have happened
1) by mistake as you were working in the home store house section you hit the floor tab then clicked on the new house floor which had turned red. This would delete the floor whole in one shot
2) going to the cloud menu you downloaded a data upload made earlier in the game. This would remove all progress done since that data backup but you would recover the 300K LP
if any of these 2 options happened there is not much to help you. It's considered operator error; if you believe none of these were done, as mentioned earlier you would have to contact FM Support
