Can a non attorney file a default judgment in New York

I truly don't know what you mean.

Do you mean file papers to get a default Judgment, something else?

I'm also in NY.

What is the situation - as much as you are comfortable posting.

Basically in a default Judgment the other side doesn't appear but the process starts with a Summons and Complaint.

You may request it, if you are the party involved, you can not do it for someone else.
But it happens in court so you would be representing yourself in court to do this

NO ONE can "file" a default judgment. A default judgment is awarded by a court when the defendant fails to respond to a suit.

So if you want our help you need to explain the circumstance so we can understand what's happening and give you the best answer we can.