My Dad 95 has stopped communicating with me! Now what?

When he accuses you of stealing whatever that was a gift, remind him he gifted it to you.  You can ask does he want 'it' back?  For the car, you can say 'You gave it to me because you're not driving any more, and I need it.  I'll have to shop for a replacement first cause I got rid of mine when you gave me yours.  Do you want it back?'  Usually, they say no, you're right about them not driving, & they want you to have it, then they'll go on to another subject.  If not, you can always say you haven't found a replacement, but if they still want it back, you'll bring it back when you do (but, of course, you don't). 

Our loved ones with dementia are suffering a lot more with this corona shut down, causing a lot more confusion for them. 

I agree with Ahmijoy: maybe cut back on your calls for a while and make them briefer.  You miss how it was; sorry, it can't be like it was; I know this feeling, it hurts.  Try not to call near sleep, naps, or eating times or times he's watching his fave show/s.  These things are at the top of their list to immediately satisfy and not be interrupted; they get irritable and more confused when any of those things are interrupted or delayed.

Hopefully, you have a good relationship with the 2nd wife and/or caregiver.  If not, that's ok, too.  Just make some adjustments to how and when you communicate with him.

It sounds like you are accustomed to spending very much time with your father. There’s nothing wrong with this, but maybe you need to be a little more independent of him. It’s possible he’s just feeling smothered. Alzheimer’s/dementia is a progressive disease. Sadly, although there are plateaus, it just gets worse. The accusations, delusions, hallucinations and paranoia are all a part of the disease. It’s a good thing you don’t argue with him. You will have to trust his wife and caregiver to take good care of him. Dial back the contact to a few times a week. If you are on good terms with his wife, email or text her occasionally to find out how’s he’s doing.