The following works if you have terminal emulators on your machine but your launcher is pointing to an incorrect one after you've jiggered things around on your box:

1. Right click the terminal launcher icon on your task bar. In the launcher window that opens, press the + icon to add new items to the launcher.
2. In the resulting dialog, there should be a text box to allow searching for items to add. Type in "term".
3. If there are any terminal emulators in the results, add one (or more).
4. Next time you click the launcher icon, the emulators you added will now execute.

If you have functional terminal emulators on your machine but your launcher on the taskbar is pointing to an incorrect one after you've jiggered things around, try the following:

1. Right click the terminal launcher icon on your task bar. In the launcher window that opens, press the + icon to add new items to the launcher.
2. In the resulting dialog, there should be a text box to allow searching for items to add. Type in "term".
3. If there are any terminal emulators in the results, add one (or more).
4. Next time you click the launcher icon, the emulators you added will now execute.