Now when I switch on the computer, only black screen with the following message shows up:

"Could not write byte: broken pipe"
.....
Starting network connection
Stopping network connection
(the above phrases repeat many times)

Also something like:

Stopping System V runlevel

I cannot type on the screen. It doesn't proceed onto anything. Just hanging there. 

Please help! If there's anything I can do to enter and get my files.

Thank you!