Reverting to previous map set.

Since you have older backups, I'm sure you'll have a backup of the current map made so that if you want to return to the current map, you can do that.

I'll let others speak up if I've missed something and suggest you wait for other replies before proceeding. On the nuvi, delete (after having made a computer backup):

-all files beginning with gmapprom. There should be a large .img, and small .unl and .gma files.

-the Junction View file which will be something like Dxxxxxxx.jcv.

-here's where I'm quite unsure. The nuvi has its voice recognition files, some/all of which are map-version specific and they reside in the ASR folder. Some/all of these will need to be deleted.

Finally, from your earlier map backup, copy the appropriate backup files from the computer to the nuvi taking care to copy each to its proper folder.

All in all, this is a lot of work and some risk to restore an older map. Can you tell us why you want to go back to an earlier map? Now that the 'Is 2017.20 out yet' thread is at Page 3, the new map may be out soon and if you could deal with keeping the current map a short while longer, it'll soon be gone and replaced with even a newer map.

How did you made this backup? Just copy files from device to computer? In this case you will have in backup files folder named maps (but folder name may depend on particular GPS model), that will contain map file. It will be huge file, 2-3GB in size for NA. Just copy this file to device (to folder named exactly like it was saved to in backup) overwriting current map file and restart GPS. File name stays this same after "official" update done with Garmin software.

There is no option to remove maps from device in Garmin software.

Edit:
CraigW, you are quicker than lighting

That sure sounds like a lot of work. I think I wait for the next map update. Maybe that will fix my problem.
I'm pretty sure that after my last map update the phone book and call history stopped working. Everything else works on the phone. I tried everything I can think of including uninstalling Garmin Express using Reno Uninstaller. Then I downloaded and installed Garmin Express again and reinstalled Map Update 2017.10. Nothing helped. I also contacted Garmin and they instructed me how to use blue tooth.
I thought that going back to the previous map version might help but I wait for the next update.

It seems unlikely to me that a map update would affect your phone book and call history. I suppose anything is possible, but I suspect something else is going on with your nuvi. Has there been a recent software update for this model?

I'm sure you have already done this but just to be sure have you unpaired your phone and then re-paired it? As alandb says, it's unlikely a map update would cause this issue but stranger things have happened so starting up a fresh pairing may get things working again.

last night.

I disabled blue tooth on both the Nuvi and the phone. After I enabled it again it asked me to pair both units and everything went back to normal.

Thank you for your advice.

Glad you got everything working again.