They're not gone. They're just not in my track view. I've never seen this happen before. I've got a new mousepad and it tends to move my mouse when I click and (Using MC6) I clicked on a track and it made it the full size of my track view. When I resized it, all other tracks in track view were gone. They're there in my Console view. I can see/hear them. But in track view (which is where I edit) they're gone. Did I do something stupid? How do I fix this?

Control+H will hide the selected track
 
to bring it back, press "H" on the keyboard (no control key).  that will bring up a menu list of all of your tracks.  the one you just hid should be listed, but not checked in the checkbox.  checking the checkbox will display it again.
 
you can change the default keyboard shortcuts and remove this (and others) by going into the preferences ("P") and going to keybindings.  assign that key to "do not assign" (or something like that).
 
https://www.cakewalk.com/Documentation?product=SONAR%20X2&language=4&help=Templates_KeyBindings.4.html

Ok. I guess something is wrong. "H", nor "Control H" does anything. Not sure what that means.

Also, going through every keybindings menu, there is no "bring up a list of all your tracks", if you're referring to the "track manager", there's nothing for that either. And I think that's sonar only, not MC6.
 
 

It looks like at somepoint I altered my key bindings to format to my mouse (which has a 10 key) and it erased everything else. There's nothing bound to H or Shift H or Control H. And there's no option I can find for opening the Track Manager or showing all tracks.

yes, Track Manager is what should come up with "H"
I'm not at home to check my MC version, but I thought this worked in MC as well as sonar.  I will do my best to try to check this tonight to verify.

looking at the online documentation for MC6 Touch (shouldn't be different for non-touch with this respect), I don't think the track manager is available for MC.  however, there are several shortcut keys which should work:
 
http://www.cakewalk.com/Documentation?product=Music%20Creator%206%20Touch&language=3&help=Arranging.05.html
 
try using "SHIFT+H" and see if that brings all of the tracks into the view of the project.

There's still no track manager. 
H still does nothing. 
I lost another track today... hours of work gone as a result of choosing Music Creator. 

Try M. That opened the track manager in older versions.