Hello,
It sounds like you have verified that if you turn one front wheel the other turns
I assume by hand?
If you believe that the front axle is okay the next most probable cause id the fron drive shaft.
The front drive shaft is not splined on each end. It has grooves with ball bearings (individual balls) that form a sort of U-joint.
It is pretty common for those fail.
So look up instructions for removing the drive shaft and take a look.
Good luck,
Jim