I know that the 401k plan is like stocks and it goes up and down and I do not want that so i was jus wondering is there an ira or a retirement plan that is interest based only.
A 401K can be be invested in a fixed income investment or bonds or any number of investments besides stocks.
IRAs can be invested in federally-insured savings or certificate of deposit accounts in addition to various other forms of investment.
These retirement accounts are arrangements that offer tax advantages. The types of investments you can choose fall within that arrangement.