so where can i find a sound card and how do i install it

To get info about possible sound card options, i'd advise posting a new thread to solicit input/advice from others on the forum

Just to give you an idea of "simple" USB sound cards (just plug 'em into a USB port) google USB sound card. (I'm a "geek" but not an "audiophile" so best to get advice from others re: specific recommendations to meet your needs and budget)

G;luck. Hope you can get a new card and get your sound back!