The drive space was changed from 29/25 to 20

[Jandj240]

Please help, on my laptop I went to right clicked on the original drive/disk that held about 25/29 space, and I changed the drive space from to 20. I restarted the laptop because after I exited put of the program thing, the laptop became slower than usual .Now my laptop will only show the usual page to put in the password to turn it on I guess, and says "windows starting" for a couple of minutes then shows a blank screen. The most important files took up at least 15 space of the original drive. I was just wondering if my laptop could be fixed, and if you could possibly show me how to fix it.
It's a windows 7 I think. I'm doing this on a tablet.

 

[DaveA]

Where did you make this change?
And why?

 

[Jandj240]

Where did you make this change?
And why?

To be honest I changed the space because I thought that would make more space in order for me to reset the laptop.
The change was made to the original disk (c) I think), and I kept right clicking to a page where I could change the size/amount of the disk.

 

[DaveA]

I can not find any that show me drive space when I right click a drive.
Can you tell us what you clicked on and what program it was that allowed you to make this change?