If you are talking 401K then you really did loose your money! All funds you invest your 401K in still buy market "shares." This means that will the value of your price per share dropped significantly, the amount of shares you own was still the same. When you transferred or moved your money into a safer fund, then you actually lost your money.
People really do not understand 401k programs at all and there is ignorance when it comes to fluctuations in the market. 401k investments are long term and you should not pay attention to daily, monthly or even yearly fluctuations. What happens when in a few years that very same fund has the dollar value double? 401k funds have different risk based funds and when you are young it is recommended that you invest in more aggressive or high risk funds as they will return more money for you. As you get closer to retirement, you want to move your money into low risk funds.
If you look at the performance of the funds in a 401k plan, they will show you since inception the 1, 5, 1o year etc performance. These are the indicators you should use to help determine if a fund is a good performer. I currently have a -2.5% return on my investment with my 401k and I am fine with that. If the market tanks, I am fine with that. Why? Because I know that it will rebound and excel between now and the time I retire! If you have a 401k, just remember it is not the same as investing in the stock market. If you cannot handle the fluctuation, then put all of your future investments in to low risk low yield funds and just enjoy the company matching contributions.