I was given meds during deployment. Now that I'm back in my home state, where do I get a refill on my prescription?

Too easy. Your pcp…
You’re probably still on Tricare from AD so it’ll be covered and in your record. Show your pcp the bottle and you’re gtg!
Alternatively you could’ve requested refills when you demobilized at your SRPC.

As a Medic I can tell you while deployed your HHC or BN PA or PCP should be the first contact.
If you are CONUS and still need them then he/she should take care of it.
IDK if you're NG, Reserve, or Active but for the former your PCP should either take care of it or refer to your civilian PCP who might talk to that doctor/PA, might want blood work, and a checkup before continuing any medications.

A lot of this depends on the prescription. If the medical issue is still on going then you should have got a Line of Duty so you would still have Tricare after you leave active duty. If it is for a minor issue then they may have just gave you what you needed when you demobed. If you needed long term care then you should have got the LOD. If it was permanent then you might have to go into the VA system. You don't really have a Primary Care Provider in the Reserve component.

https://www.tricare-west.com/content/hnfs/home/tw/prov/auth/lod.html

Through your DR