A pink line appear on my laptop Sony Vaio screen few days back.
I tried to resolve this by formatting my machine but it still appear. I think this is a hardware issue.
Please help me to fix this.
It is most likely related to a physical hardware issue. You will have to replace the component in question, which will require more trouble shooting on your end to find out what it is.
You have a row of dead pixels. There is a program that is supposed to "excite" the pixels to coax them to working again, it may be worth a try, the times I have tried, it did not do it for me. You will need to replace the LCD panel. It is an easy (most of the time) DIY replacement.
While you are searching for a solution, you can also install flux to temporary calibrate screen color.