Long-press the Scale Tool icon to reveal the hidden Shear and Reshape tools. A Pro Tip: The "Transform" Shortcut
Below are the documented reasons for the tool being inactive, ranked by probability of occurrence.
If you can’t see the tool at all, remember that it is nested under the in the toolbar. why is the shear tool greyed out in illustrator
The Shear Tool that are not in a special editing mode.
You clicked into a text box with the Type Tool. The Shear tool is greyed out because you can’t shear individual characters while typing. Long-press the Scale Tool icon to reveal the
The most frequent reason the Shear tool (and many others) appears inactive is that
If you are trying to shear individual anchor points rather than the whole object, ensure you are using the right tool. The Shear Tool that are not in a special editing mode
If you have the Text cursor active (blinking cursor inside a text box), Illustrator restricts tools to those relevant to text editing.
This opens a dialog box where you can input the exact angle and axis you want. This is often faster and more precise than using the manual tool. Summary Checklist Is the object ? Is the layer unlocked ? Are you out of Isolation Mode ? Have you tried the Object > Transform menu?