How to fix it..

Question

a vertical line appears when I log in my
laptop.

Answer 1

contact your laptop service center..
https://appuals.com/vertical-lines-on-laptop-screen/

also you should know this Q/A area for programing related questions.. Please use the "share anything coding" feature found at the top of the activity feed to make posts like this.
Review these guidelines:

https://www.sololearn.com/Discuss/1316935/?ref=app