My ubuntu 16.04 interface has changed

A few days ago I booted my ubuntu 16.04 on VMware, it seemed to be normal at first.




But the problem happened after I maximized the window size.
The wallpaper size didn't maximize along with the window size unlike it was supposed to.



The size of background was maximized normally when I changed the wallpaper to others.
Also I found the size of folder icon was also changed.



They weren't like above before a few days.
The folder icons got bigger and 'Computer', some menus(Computer, Pictures, Music....) on the left sidebar disappeared.
I remembered that they were like below:

(It's not from my computer, I brought this from googling)


I tried to change the icon size in settings but still different with before.
I think it's just not a problem of icon size and wallpaper, but something happened to interface setting or drivers....I don't know why.
Is there anyone had a problem like me and solve it ???