in my system in device manager an yellow question mark appers on the corner of sm bus controller and audio is not working kindly help me to solve this problem
Before anyone can help you, you need to post the specifications of your system so we can better know how to help you as each system is different.
If your system is a Brand name, then we need to know the Brand and model number. If the Operating system or hardware has been upgraded, then we'll need to know this.
If it is custom built, then we'll need more information such as,
Motherboard manufacturer and model number, processor, amount of memory and type of memory, video card/s are installed network adapter, Operating system.
Just pretty much the basics so we know what we're dealing with, otherwise we won't be able to help you.