Where can I get the 2.5mm headphones?

Hello guys. A long time back I went to Ireland and I bought an mp3 player from there. It had the headphones with it but those headphones are now in a very bad condition. Those were 2.5mm headphones and now I am not able to get them in any of the stores here in America. All that I am getting are the 3.5 mm headphones. Where can I get the 2.5mm headphones? Is there some online retail accessories store that can help me in this case. I don't want to keep that mp3 player of mine idle. Please help me!