Are you having Audio problems or WiFi problems?
Why would you replace the audio card for a potential WiFi card problem?
Have you tried pressing F7 to disable Airplane mode and see if this enables the WiFi?
Check Network configuration page (Settings > Network) to ensure the Wi-Fi switch on the Network configuration page is toggled to On
Check in BIOS to see if there is an enable/disable setting for the WLAN.
If all these are OK then here is a link to the ifixit Lenovo Yoga 2 Pro Wireless Card Replacement guide. to check if the WiFi card is seated properly into the connector.
Be careful when you do this as the battery is still connected to the systemboard. DO NOT slip with any metal tools that you may use.
To be safe disconnect the battery first. You don't have to remove it just disconnect it.
If it seems OK the WiFi card may be faulty. The card information should be printed on the card. Search online for suppliers of a replacement card
What OS is installed in the laptop?