Then you better start BUYING! MY 401(K) IS DYING!..............
Don't sweat your 401(K). If you have it in stocks, it's because you won't need the money for a very long time, and the market will come back.
If you need the money next week, you should have been in bonds already, and the stock market shouldn't matter.
Just don't panic and bail out now. The time to get out has passed, so now you just need to ride it out. If you sell now, you'll only buy back in later at a higher price, and the same money will buy fewer shares of your favorite mutual funds.
Had you sold out a year ago at the peak, now would be the time to put the money back in, so in either case you'd be in the market right now.
If you had put all of your 401(k) money into nice, safe T-Bills your entire life, you'd have less money now than you do even taking the recent crash into account. So relax!
(I'm selling if the market ever gets to 12,000 again...) ;^)