I have used all my Pokéballs to catch Pokémon. Now I'm trying to get more Pokéballs, but don't know how. I can't see any gym or Pokéstop on my map either. Is there any way to earn Pokéballs or will I get them on a daily basis?
As far as I know, most or all PokeStops and Gyms in Pokemon Go are taken from the game Ingress, which had few set Portals from Niantic and most Portals requested by Players. Which leaves a possibility that no one ever set or requested Portals at your location.
If you and your friends are certain, that there are no connectivity or GPS issues I second dly's comment:
Until recently you were able to request Pokéstops, but apparently they took it down again. If you have no stops in your area at all it might still be a good idea to submit a ticket at support.pokemongo.nianticlabs.com/hc/en-us – dly 3 mins ago