I didn't pay my overdrafted bank account for too long and now I can't pay. How bad is it to fix?

So I overdrafted my account and didn't repay it for over a month. Today i went to finally pay and ATM said my card wouldn't let it make the deposit. How bad is this and what would I have to do to fix it? Please no stupid answers like ';Very bad'; and I already know what I should have done.