Take as much cheese as you need out of the airtight container or freezer bag. Leave any extra balls in the container/bag, seal it up, and put it back in the freezer.
Put the balls into another normal plastic bag.
Fill your sink with cold water (not warm.)
Put the bag in the water and leave alone it for 30 minutes.
After 30 minutes, replace the water with fresh, cold water. Leave the ricotta alone for 30 minutes.
Gently squeeze the ricotta cheese to check if it's thawed. If not, repeat Step 5 until the cheese feels soft.
Open the freezer bag and unwrap the ricotta ball(s). Put the balls into a mixing bowl and stir the ricotta cheese well.
Eat or use the cheese in a recipe within 2 to 3 days.