How Replace CMOS Battery in Sony Vaio VGN-FS742 / PCG-7D2L?

If it's an IDE? Newegg has a 320GB. SATA can go much bigger, but Sony linked your model to a IDE hard drive.

http://www.docs.sony.com/release/994630300_Rev_D_NO_PHONE.pdf

Most likely either the power cord/charger for your computer needs to be replaced or the motherboard in your laptop died.

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.

Hello,
Please open you vaio laptop from bellow instruction link.
http://www.insidemylaptop.com/how-take-apart-sony-vaio-vgn-sz-series-laptop/

Follow step 14
You can manege the idea about CMOS battery.

http://www.insidemylaptop.com/disassemble-sony-vaio-vgn-bx-series-laptop/

Follow step 11

But this is your actual model
http://www.insidemylaptop.com/?s=PCG-K33+PC+Notebook
Just remove the Cmos battery And wit 2 minutes again fit the battery .Your password will be soon reset.

Hope it will help you.

They are usually right along the front of the laptop so best way to get it to die is to remove all power sources for a few days/weeks and have it die out.

Try to remove the battery, remove AC adapter, and press and hold power button for 45 sec. reinsert battery, and Plug and try again, if that doesn't solve it, you may need to try to change memory first, (cheapest) or the motherboard or CPU.

Please give good rating if this helps your issue, Thanks

It is always is. CMOS battery for replacement.

Did you spill something on it? (the most common cause of this issue).

try cleaning it with dry cloth, compressed can of air, etc......NO WATER/CHEMICALS.

if that don't work, take it to a shop, or if it's still under warranty, get it repaired/replaced directly from SONY.

That's a common problem, it's not hard to fix. You'll just have to swap it out. You might be able to find a guide somewhere online but if you just use common sense you should be able to just take the laptop apart and do a swap. Just pay close attention to HOW you got it apart. Ebay is the cheapest place for replacement parts and the K33 is one of the best Sony Laptops ever made btw.

Sorry the laptops fried, the best thing you can do now is remove the hard drive and get your data from it if it still works.
buy a new laptop and sell yours for spares on ebay

Kind regards