While running a fullscreen app in Wine such as games, you might not get the screen resolution back after you close the app. It’s because Linux won’t automatically change it’s resolution like Windows.
But you could if you run a simple file in terminal. Here is how you could do it.
Create a file named normal.sh in your Desktop with the following contents:
#!/bin/bash
xrandr -s 0
Save it on a place where you can open it easily. Make the file Executable to run it in a terminal. See this post to see how you could make a file executable.
After you run a full screen program and closed it, run the file we created to return back to the normal resolution.
If you get a dialog like above when executing the normal.sh click on Run in Terminal button.