Three possibilities come to mind:

1. Those tools are undockable and you might have accidentally dragged them elsewhere
2. They got dragged further up the left side bar somewhere - I've done this and flipped them with the other controls on that bar by accident before.
3. They got hidden somehow

For the first two I'm not sure what you can do... look around your 3D viewport and see if they are somewhere else on-screen maybe?
For the second, try right-clicking on the left hand menu bar and see if "Image Tools" is checked - if it isn't, it should be. If it is, try un-checking it and then re-checking it and maybe they will come back.