You do not enter 0 for yiur prior contributions if you have not previously withdrawn all you your prior years contributions. It is asking what your total prior contributions were prior to the current distribution. There is a separate question that asks the current value of the Roth and that would be zero if you closed the account but that is a different question.
If your prior contributions totaled 20K and you have not already withdrawn any of that then enter 20K. Only the 2K of earnings will be taxable if you are under age 59 1/2.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
