FYI, always list at least the year of your Jeep. While the Jeep JK (2007–2018) models share a similar HVAC system, there were minor wiring and resistor differences across the years.
Start with checking the blower motor resistor, as it’s the most common failure.
If that’s fine, test for power at the blower motor with the fan on.
If neither of those is the issue, then it’s likely the fan switch or wiring.