ignorant
A person who ignores important things could be described as apathetic, negligent, or careless.
A person who buys a lot of things is often described as a shopaholic.
An optimist.
stupid, loser
A person who thinks nasty things could be described as pessimistic, cynical, or having a negative mindset.
A person who collects things is typically called a "collector" or a "collector specialist."
A person whom always puts things off is called a procrastinator.
All depends on what it was that you did. The circumstance might call for an apology in person, or a call over the phone. Then it might just require a card or a gift of some sorts. The important part is that there are things to do to make things right.
A person who makes of
collecter
Ambitious
A person who hoards things that you have would be called..."you." Or whatever your name is.
A person who looks on the gloomy side of things is pessimistic.
You could call them generous or a recipient or a patron.
Human.
An idiot.
A sybarite.
Smart