Your number one priority is to recover your data, so here are steps I would take considering you can not get your machine to boot. I included some options since I don't know what your technical situation is.
1) Remove the computer's hard drive (HDD).
This is where all your information is stored and it can be accessed from a separate computer. Here is a link to a disassembly guide: http://www.insidemylaptop.com/complete-disassembly-instructions-hp-pavilion-dv7-laptop-guide-2/
You're in luck since your laptop is disassembled rather easily, but please be cognizant that the tiny laptop parts are sensitive and don't use too much force. The screws are not so small that you can't use normal small screw drivers, but you may need a set of precision screw drivers, sometimes called jewler's screw drivers.
2) Buy, borrow, or steal any device that will allow you to plug your hard drive in as a USB drive such as an enclosure or this transfer cable:
http://www.amazon.com/StarTech-SATA-Drive-Adapter-Cable/dp/B00HJZJI84/ref=sr_1_1?s=electronics&ie=UTF8&qid=1453595732&sr=1-1&keywords=sata+to+usb
NOTE: DO NOT ATTACH THIS DISK TO AN UNPROTECTED WINDOWS MACHINE. You run the risk of infecting the other machine too...
If you MUST use a Windows machine for file recovery, be sure to install any of the anti-malware programs recommended on these site PRIOR to connecting your hard drive.
http://www.2-viruses.com/remove-white-screen-virus
https://malwaretips.com/blogs/remove-white-screen-virus/
3a) If you have a friend who uses Linux, awesome! Simply plugging your hard drive in will give you access to your files.
3b) If you do not have a Linux using friend, download a Linux operating system, burn the installation software to a DVD. The popular modern distributions will run from the DVD and will give you access to your files. Linux operating systems are not susceptible to Windows virsus, additionally, some distributions come with ClamScan AV which can scan your files for, and potentially remove, viruses.
Here's a link to Ubuntu Linux:
http://www.ubuntu.com/download/desktop/thank-you?country=US&version=14.04.3&architecture=amd64
How to make a bootable dvd from Windows:
http://www.ubuntu.com/download/desktop/burn-a-dvd-on-windows
How to make a bootable dvd from Mac Os X:
http://www.ubuntu.com/download/desktop/burn-a-dvd-on-mac-osx
4) Please remember that your data itself may be infected. As such, make sure you install any necessary anti-malware programs BEFORE you move your files.
5) Now that your valuable data is (hopefully) cleaned and secure on a separate, uninfected machine, you can 1) perform a happy dance and 2) start trying to fix your laptop. From what I understand, you are not seeing the power on self test when you are turning on your computer, in fact you're not seeing anything at all? I'm not familiar with the white screen virus, but a brief search has not shown me anything suggesting that it infects the BIOS, so perhaps these are two separate, if related, issues.
My number one recommendation for your laptop is to reset the CMOS. The way to do this effectively is to unplug the laptop, remove the battery, hold the power button to make sure any residual charge is drained, then open the laptop's case and remove the CMOS battery (Refer to disassembly instructions from Step 1).
After you replace the CMOS battery, try booting the laptop again. You should at least be able to access the BIOS. From there I recommend formatting the hard drive, reinstalling Windows, and transferring your files back.
I hope these steps work for you!
For future safety, I strongly recommend that you back up anything you're not willing to lose. Hard drives die, viruses happen, and if you do not have at least ONE back up of your files, as time goes on it becomes increasingly likely that you will lose EVERYTHING.
I personally don't have any files that are classified/proprietary/sensitive to being stolen, so I use cloud storage as backup.