Sony Vaio PCG and some Vaio VGN Series use the last 7 digits of the laptop serial number to calculate the bios master password. The serial number for a Sony Vaio is often located on the bottom of the laptop on a white sticker. The serial number may also be found by removing the battery and checking in the battery compartment. The link to unlockbiosrecovery.com below works on the following models:
PCG-C, PCG-F, PCG-GR, PCG-GRS, PCG-GRT, PCG-GRV, PCG-GRX, PCG-GRZ, PCG-N, PCG-NV205, PCG-QR, PCG-R, PCG-SR, PCG-SRX, PCG-TR, PCG-V, PCG-VX, PCG-X, PCG-Z, VGN-B, VGN-FS, VGN-S, VGN-T, VGN-TX1, VGN-X
I use http://www.unlockbiosrecovery.com/Unlock_Sony_Bios.php
For $20 they use the last 7 digits of the laptop serial number to calculate the bios master password and then email it to you in an hour. They guarantee it to work and you can call them if you have a question.