I am presuming that you helped someone and instead of being grateful they showed something else, it’s not old fashioned to have appreciation showed, it’s a human need sometimes. You know , in the past, when this has happened I remind myself why I did what I did in the first place. What prompted you to help.
Also think about what happened before this, I often found that timing was often spiritual. Could it be that you had experienced positives, and this situation arose. Also think about the best way to handle it, people let us down all the time and we have no control over how they react or respond , but we can make choices with regards to how we handle the negatives on a personal level. There may have been all kinds of reasons why appreciation wasn’t shown, we all have our battles with pride and sometimes that leads to us not saying what we should.
I use to sulk when this kind of thing happened, also would feel sorry for myself, would get so angry inside ( it use to happen at work a lot ) I would eventually remind myself that its God I work for and do things for and who knows who else is seeing that kind act -