The most likely cause is either a blown fuse or a bad blower motor resistor. with the outside chance of a control head.
the resistor is located behind a kick cover on the passenger side.under the dash.
the fuse needs to be checked first. It is a 40 amp fuse in the fuse box under the hood. Your owners manual should show you which it is if it is not inside the cover.
All right, Turn the key on and set the blower to high.
If you have a test light put the clip to power and use the probe end and put it in the the back of the blower motor connector at the black wire. and see if it lights. If it does then switch it to ground and see if you have power on the green wire.
If you don't have a test light take a piece of wire attach it to Ground and again but it in the black wire side of the connector. with the motor connected and turned on the motor should now power up If you have power on the green wire (fed from fuse)
With either of these tests you are testing the ground side of the motor. The resistor and control head are on the ground side.
The next step to test will be to take the resistor and disconnect. here you'll need a test light attached to power now test for ground through the control head. if you have it then the resistor is bad if you don't have ground you need a blower control switch or control head.
You are very welcome.