the front cam on my vaio svf15218saw is not working since i installed win 10

Is this the laptop were talking about? Where the W at the end of your model number denotes that it is white. Though you would benefit greatly if you could specify your systems specs in case you have an AMD/Nvidia graphics card onboard i.e for driver support.

Did you install Windows 10 via an upgrade or as a clean install? Have you downloaded all the necessary drivers meant for Windows 8.1 off of their driver download site? I asked to download 8.1 drivers so you can install said drivers under compatibility mode. There is also a BIOS Update version R0230DA with a release date 08 May 2015 which you should update prior to your driver installations.

Right click installer>Properties>Compatibility tab>Windows 8 [from drop down menu]

If you've updated all your drivers(including chipset) then go into device manager and see if there are any notifications that pop up with a yellow exclamation mark. It should show up in either the other devices tab or imaging devices. If you do then right click and uninstall/delete the hardware from that list. Windows will ask you to reboot your system upon which the new drivers should be installed.

You should then use a third party app like Skype to see if the webcam is functional.