Microsoft has improved the tablet mode on Windows computers. It works like a charm and offers several features. For instance, the icons become big when you activate the tablet mode. That goes for Start Menu as well, where a full-screen menu replaces the usual one with no desktop. It’s done to ease your tablet mode usage.
However, sometimes, a user accidentally activates the mode causing the Start Menu to get stuck in full-screen mode. So you have to disable it. For that, follow these steps:
Step 1: Open Action Center on your computer by clicking on the right-most icon in the taskbar. Alternatively, press Windows key + A to launch it.
Step 2: Look for Tablet mode option. The blue icon indicates that it is on. Click on it once to turn it off. If the Tablet mode option is missing, click on Expand to view all the buttons in the Action Center.
Now, I believe that should solve your problem. However, if you are still having an issue with the locked windows screen, kindly let me know in the comment section below and I will try in responding to you with an available solution as soon as possible.