Dry ends can bring down even the most amazing hairstyle. A number of factors may be in play here: color or overprocessing, too much heat, lack of proper conditioning, neglect and infrequent trims. Unless your ends are damaged beyond repair, usually due to an irreversible process, they may be salvageable, even if you think all hope is lost. Don't expect a fix, but it'll carry you to your next cut.
You don't necessarily have to cut all of your hair and start over. Major cuts are painful for women who've worked to gain some length. But it will actually make your hair grow slower to not cut it. You should be able to trim a little at a time—half an inch or an inch (for the very brave) each month, while simultaneously conditioning, will gradually bring your ends into perfect shape. You might want to visit a professional for a trim so that your results are even, but it's easy to worry that a stylist may cut too much. If you're that kind of person, just trim the hair yourself, but only trim away away excessively dry ends while your strands recover.
The first thing you need to do on the step to getting your hair back to normal is work out your conditioner situation. Even if you think you've been conditioning your hair well, you still might not be giving thirsty tresses as much moisture as they need. Too much thermal styling, the styles you wear, and even scarves, and coat collars can destroy ends. It's easy enough to reason why: these are are the oldest parts of your hair, and so are already prone to dryness. Don't make them worse by skipping essential conditioning. This includes rinse-out and deep conditioning products, or hair masks. If your hair is really suffering, put it on a deep condition program right away. While some deep treatments work in a matter of minutes, look for those that work in conjunction with low heat for maximum penetration.
If you're not currently using a leave-in conditioner after each cleansing session, now's a great time to find one that works for you. You could also try the baggy method, which just means putting a baggy or showercap over your head whole a moisturizing product like a deep conditioner or mask is on. It doesn't have to be either of those though, natural oils can work too. Try bagging your ends a few nights per week to start. After a few weeks, check to see if there's any improvement in your mane's moisture levels. Once your ends are less brittle, you can cut out the bagging altogether or just do it less frequently.
With the exception of cutting them off, it can take a lot to coax thirsty ends back into shape, so don't expect instant results with any method. After all, your hair didn't lose all moisture overnight. Practice a lot of patience, along with serious TLC, and your hair can gradually come back to a healthier state.