Do I have to file if I had no income except for interest earned on IRA accounts, or interest on a money market account that is less than $100 dollars?

No, if your total interest earned is less than $100 you do not have to file a return.  If you did not take any early withdraw retirement plan distributions that were subject to a penalty, and you have total taxable income of less than $12,000 then you do not need to file a return.  If you are over 65 you would not need to file if you have taxable income of less than $13,600.

When you say earned interest, are you talking about just the money market account, or all accounts combined?

Anything interest that you actually received.  If you did not withdraw from the IRA, it would not be counted.  If you withdrew from it, then it would be.