It takes a long time. My experience with a 99 year old stroke patient ended up with two years before she could speak. That was with daily encouragement. She is now 110 years old.
Hi!
I am sorry to hear about your father’s medical problems. Post stroke the residual neurological symptoms and speech may improve or it may not. It depends on the location and size of the defect causing the stroke. You must take him to a speech therapist and his neurologist to assess whether speech will come back or not. Speech therapy, physical therapy and motivation is important for recovery. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.