If the whole block has heaved, it might be possible to flip it over, excavate the root and apply an aggregate base, then flip the block back into place. That block weighs over 400 lbs, so ask for some help from a neighbor if possible.

If the block cannot be salvaged, break it up and dispose. You can repour the section using about 5 bags of premix cement. You need about 5.3 cubic feet of quickcrete. Even with the purchase of a float, edger and some forming lumber the project should cost under $40 DIY. Do not build a ramp up to the cracked section, the uneven ramp would not make your insurance company happy, and the raised block will be unstable and may continue to move. You need to use an axe or adze to remove the “root” of your problem.