Thanks for writing in.
I am sorry to know about your father. Did he have thyroid cancer
when he was operated? Does that mean that it has come back? Where all it has spread?
Even if it has come back, we have options of resurgery and/or radioiodine therapy.
I am not sure why he can't speak. It may be due to injury
to the nerves during surgery or cancer infiltrating voice-box or removal of voice-box due to cancer infiltration.
Regarding your specific query about thyroid gland transplant, it is very unlikely that it would ever be done as after thyroid removal just thyroxine
hormone replecement is enough for lifetime. There is no need to do such a complicated procedure like organ transplant. Removal of thyroid itself cannot lead to loss of voice as I mentioned.
If you can send more details, we can guide you better.