16.04 - My desktop icons are large, and menus and background look differnet

I upgraded to 16.04 last week. After a daily update I rebooted my laptop and I found that my desktop icons look larger, my desktop wallpaper is changed to black and my menu looks classic.

I thought the problem was with Nvidia driver, so I removed it and reinstalled it, but the issue persists. Please, any idea can be helpful.