Tracks are not easy to edit. There isn't always a quick change that you can make without it damaging the track in some way. These types of things take trial and error to figure out what works and what doesn't, what can easily be manipulated and what effects other things. If you are going to mess with a track there are some things you should consider.
1. ALWAYS backup your track. Keep a copy of the original on hand. When you make an edit, and it works, back that up too, because eventually you will break something and it gives a better starting point than from the beginning.
2. If you run into problems, read through the forums to look for other people having the same problems. Most problems are common and frankly people get tired of answering the same questions over and over again when that information is available to them already if they just look for it.
3. When you really are stuck, and can't find an answer, and post it here, do not under any circumstances just say "i edited a track a little bit and now it says "failed to open track" is there a way i can fix it?" We have absolutely no clue what you "edited," so how do we know how to fix it? My point is, BE SPECIFIC. Talk about what you are trying to accomplish, what you actually did, and what the actual result of that action was.