[ Branched ] Illustrator won't let me use anything.

Some problem happend to me. Here is what I did:

Set the workplace to "Essentials"

That's it, all the tools that didn't work now start to work.

Hope this helps you too.

councilu23234117  wrote I click it. I click, I click, I click. Nothing happens.

Where is your pointer when you're doing all that clicking? On the tool? With the tool chosen and active, you must either:

• Click on the artboard to bring up the Rectangular Grid Tool Options dialog, or...
• Click/hold/drag (on the artboard) to draw out a grid.

Not sure what you mean by all tools, but guessing you are using this tool.

You then need to click  drag and hold on  a layer that is not locked, to draw a new rectangular grid

You can use the up & down cursors keys to add or remove grid lines.

Release  mouse when you like what u see.

Can we see a screenshot if you need more help, that is usually very helpful and gives us a hint or helps explain your situation.