Mari, if your door is younger than 25-30 years or so old, you should be able to get replacements at your home center. You may have to get a different brand, and they may not be an exact match, but hopefully they will be close enough to work. If there is any question, replace both the track and door hardware. They will not be wildly overpriced and parts usually cost more than a whole unit anyway.
It is usually better to replace these with new hardware every so often because trying to bend the old metal back to the right shape is rarely successful for long. After the old metal hardware was bent, it wants to go back to the incorrectly bent shape easier than stay in the correct shape.
You will have to remove the door and removing some of the moldings should allow that. You may have to cut out a "window" in the drywall if you have to replace the track. Sorry for that bit of bad news, but there is a lot of info on repairing holes in drywall on the web. You can try to replace with the old piece, but chances are that you will have to cut a bigger and differently placed "window" than you originally thought. That makes replacing with the piece that you took out harder, but it still can be done. One other thing to watch is that the drywall patching does not interfere with the door or it's operation. Regretfully, I had to learn a lot of this the hard way. That's why our pocket door is in storage in the basement.