Websterz,
I know first hand what your father is going through. Five years ago I woke up one morning and my right side was paralyzed. Walking was difficult and my hand was useless. I made it into my office and typed out an email with only my left hand telling my boss that I wouldn't be in to work that day, then proceeded to drive myself to the hospital, about 2 miles away.
They ran a bunch of tests and after a couple hours told my I'd had a stroke. Actually, at least two of them. I was living at our house in New Mexico at the time and my wife was in St Louis, so I was all alone. We made travel arrangements and I was soon in St Louis for surgery.
I could not use my right hand, the fingers were curled inward into a loose fist, I couldn't straighten them. I couldn't feed myself or sign any papers. Simple tasks suddenly became near impossible. Like your father I had trouble with words. I knew what I wanted to say but no longer had the vocabulary.
Over the next several weeks I practiced writing. I walked several times a day, not far at first, but kept stretching it out as far as I could. Walking was the first thing to improve and I could almost fully open my hand. After about a month I could finally sign my name. Other writing and typing quickly followed. My vocabulary also recovered though I still have problems with words to this day.
I still have difficulties, mostly reading and writing. But also my fingers don't work quite as well as they used to. Last year I was offered and accepted the position of database administrator within my company, a promotion of sorts. This was after the stroke.
I'm telling this so that you will know, and you can relay it to your father, that he can recover from this. There will be a point when things get much better. But he has to practice, he can't give up. He can lead and enjoy a normal life. Some things will be different, certainly, but it doesn't have to keep him down. The brain has an amazing capacity to repair itself, but it has to know what is broken. So keep trying to do things he did before, be safe, but keep at it.
I offer your father, and your family, the most heartfelt and sincere wishes for a speedy recovery and many more years of love and life together.