First, find out if it is the camera or the lens.
While empty of film, shoot until it fails and then take off the lens. Using a small flat screwdriver that you have handy gently turn the focusing screw in the back of the lens. If this turns easily then the problem is most likely in your camera.
If the problem is in the camera, make sure that you have good batteries, then with the lens still off the camera gently turn the focus driver near the bottom of the camera- it should turn freely.
If the driver turns freely then try toggling the manual/single/continuous shooting mode switch to see if that will clear it up.
If the focus driver is stuck (and there is no visible impediment to it's turning) then you can either send it in to be repaired or just get another one. Used film cameras are cheap- check e-bay.
HTH
mike