According to you, an audio driver Realtek is already installed to your G450 laptop however still no sound is coming out of your computer. There are two possible reasons why you're still encountering this. Driver is not properly loaded or incorrect driver was installed. You may want to try the following steps I have below:
1. Go to this link
where you can download and verify the correct audio driver for your Lenovo G450.
2. Once you get there look for Audio
, then you'll see all the drivers available. Note:
You will notice that there's no Realtek audio driver there. Everything is Conexant Audio Driver
. There's a possibility that you have incompatible audio driver for your hardware. So, uninstall the current driver that you have and try downloading the Conexant audio driver. Make sure that you'll select the one which is for your specific Operating System and version.
3. Just click on the name of your selected audio driver.
4. You'll have the option to click on download.
5. After downloading it to your PC, install it.
6. Finally, after installation make sure to reboot your computer.
This should fix the problem that you have with the audio. Hope it helps.
Thank you for using Fixya.