The VAIO PCG k415s has a long history of LCD screen inverter failures. Is your screen white, or dead gray. The inverter costs us $72, but some charge as high as $140. Sony charges $155 to replace it at their tech center.
You can replace the inverter in other laptops such as Dell and IBM for half that.
The job is tricky enough that you should have it done by someone who has knowledge in that area, AND who can get the part, which is difficult.
Try out other failure possibilities first. Another possibility is hard drive failure, so first try booting to a floppy, and then another hard drive.

I doubt the problem has anything to do with Linux, but think through everything you did to be sure it isn't a silly mistake.

The VAIO PCG k415s has a long history of LCD screen inverter failures. Is your screen white, or dead gray. The inverter costs us $72, but some charge as high as $140. Sony charges $155 to replace it at their tech center.
You can replace the inverter in other laptops such as Dell and IBM for half that.
The job is tricky enough that you should have it done by someone who has knowledge in that area, AND who can get the part, which is difficult.
Try out other failure possibilities first. Another possibility is hard drive failure, so first try booting to a floppy, and then another hard drive.

I doubt the problem has anything to do with Linux, but think through everything you did to be sure it isn't a silly mistake.