If the berry bush is completely empty, your only chance is to put every adult at the research table to get enough points for level 2 of Farming. If you have any children, you can have them pick mushrooms for food, and that might help prevent starvation. Also, it helps if you put your game on 1/2 speed. The villagers will be more efficient at that speed.

The big mistake that most people make is trying to go for puzzles and other technologies, or grow their population too quickly, before there is a reliable food supply. The first priority has to be survival, and that depends upon good sources of food (which only improved farming technology can provide).

You can check the Virtual Villagers Guide to get some good basic strategies.