In the knight's castle level I got the dragon's gold with help of the knight (diverting dragon) and time traveler without getting the key of the dragon's door. Still the dragon somehow gets loose, kills everyone and breaks the lift. The problem is I forgot to get to that cave painting I was supposed to get using that elevator, which the dragon broke. So is there any solution for this?
Unfortunately, the elevator is the only way to reach that particular cave painting.
If the elevator is indeed destroyed, the only way to reach it is to start over with the Knight in your group again. One alternative that may, or may not, work, depending on the status of your save, is to force close the game without saving. This would depend solely on the latest auto-save, however, as that is what it would load to when you continued your game. If the auto-save is after the elevator was destroyed, restarting is the only option.