a blue vertical line in my macbook pro..

Make a screenshot. Press Command, Shift and 3 keys, and it will show up in your desktop. Open it and check that this line shows up. If not, your display or display connector are damaged, and if it appears, your GPU is damaged. Take your Mac to an Apple Store or reseller

The GPU is your graphic card. As this line doesn't appear, the display got damaged. Take the MacBook Pro to an Apple Store or reseller. In the case of the MacBook Pro, the display is cheaper than your GPU, as your GPU is soldered to your logic board

@ rjpmt,

Most likely this is LCD screen related failure.

If you have a mini display port adapter, you cat test your laptop with an external monitor.

If external video has no line, this is LCD screen failure. You'll have to replace the screen OR use it as is with the line.

rjpmt wrote:

does that cost to much? does reformatting won't solve the problem?

As I said before, most likely this is LCD screen related failure. If that's the case, reformating the drive will not help.

The LCD itself cost about $100 but it's not easy to replace on a unibody laptop.

I guess you can use Apple flat fee repair service to fix it.