Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
Your pinter does not have built in wifi. This is an older model that lacked full wireless support, and would require the addition of an external wifi dongle.
Unfortunately, there is no support for these printers in any form. Parts are all long discontinued, and lexmark stopped making printers many years ago, nearly going bankrupt because of the poor quality and low sales.
Even if the wireless card could be found, it would not be worth the investment. It was a $50 part, and for a 2007 model printer that was built for a 3 year service life (ie: it is surprising it has lasted this long, and likely won't last much longer). You would be better served by either using it as-is, in usb only mode, or replacing the printer entirely.
You could get a brand new and updated printer with a fresh warranty from a more reputable brand for about the same price or little more than you'd pay to upgrade this one.
If you'd like more info on any of these options, just let me know.