My earplug pin broke off inside the unit
Can I disassemble it to repair?
It depends on the model of the ipod touch as to how difficult it will be. If its a 4th Gen, then it would be a very simple repair. You can simply heat up the glass, gently pry it up, remove the metal mid frame, take out one screw...and then the headphone jack will pop right out and you can use a paperclip to push into the hole on the back side of the jack and it will pop out any blockage very easily.
You can use the guide here to get it apart. iPod Touch第4代耳机孔更换
If its an older generation iPod then there are similar guides for them but I havent personally had to repair the headphone jack on any of them yet.
Hope this helps!