Why does my computer boot up different?

My computer used to boot up normally, and by normal I mean it brings me to a blue screen and says "welcome" in white text. Then it loads up as normal. Also, when I pushed CTRL + ALT + DELETE it automatically brung me to Windows Task Manager. Now, it brings me to a screen that says "Shut Down, Task Manager, etc." The top of the start menu also used to say the computer name with a picture, but now it's just "Owner". When it boots up now, it asks for a password but there is no password, so we just click Sign In. I'm not sure what I did, but the last thing I remember was I went into the connections -> properties for my internet and installed and then uninstalled Client for Microsoft Networks. I also have myself a static IP. What could've caused this? My dad wants it back to normal.