You have to tell us more facts.
The minimum is exactly which Mint you have - which version and which edition
(main or any of the CEs)
We also need to know a bit about all your hardware.
Run " lspci " in a terminal and post here (to avoid misunderstanding - the first character is a minor L and you copy by marking with the mouse and then right click)
Some wifi and possibly built in sound can be connected to USB even if they are internal - if you suspect you have one of these run " lsusb " in a terminal.
Also tell us if this is using mint4win or not, quite important
And if you have Intel sound ICH7 or higher this is probably the solutionviewtopic.php?f=48&t=17801&p=107982&hilit=ich8+alsa#p107982