I used illustrator the whole day without any problem. The last time I opened it, I think it got an update (to the v. 26.3.1) and then I started havening problems. In particular, I noticed that with the selection tool and the direct selection toold the canvas gets stuck: I cannot either move a point and/or an object or deselect by clicking outside the selection. However, the side panels keeps working and thus I am able to release the selection if I select another object directly from the layer panel. But when I get back to the canvas, it doesn't work any more. I have both closed the program and restarted the computer, but the problem hasn't been solved yet.
We are sorry for the trouble. In addition to @lambiloon suggestion, you may try resetting preferences. Disclaimer: Please note that resetting preferences will remove all the custom settings, and Illustrator will launch with default settings.
If you are using an external monitor(s) with a laptop, please check if unplugging them & then restarting the app and working on your device's primary screen resolves the issue or not?
Kindly update the discussion if you still need assistance with it. We'd be happy to help.