My dad lost his voice for many months now, he got nodules and we are so stressed.

My dad 64y/o lost his voice one day, he have nodules and GERD. The problem is that we have lnly one speech therapist in the city and the techniques he taught to my father doesn't work after so many months, if someone have videos or pdfs or any ressources of any techniques that he might try please share them with me. Also, is the surgery very safe ? What are the types of them and what can he expect from it ? Thank you very much we are so stressed because of his illness.