I want to make it so if you right click the block it turns into another block but I have that, I want it to give you an item if you right click it and it has a cherry it gives you a cherry.

I did this in 1.6 but i dont remember and i lost the files

public boolean onBlockActivated(World worldIn, BlockPos pos, IBlockState state, EntityPlayer playerIn, EnumFacing side, float hitX, float hitY, float hitZ, ItemStack stack){

	 int i = pos.getX();
     	int j = pos.getY();
     	int k = pos.getZ();
     	BlockPos bpos = new BlockPos(i, j, k);

	 if(this.hasCharry == true){

		 worldIn.setBlockState(bpos, MoreOresModBlocks.charry_leaves_empty.getDefaultState(), 0);
	 }
	 return true;
 }

Just use World#setBlockState with the original pos(BlockPos), you need not create new instance of blockpos copying that.

Also for giving a player an item, here is a snippet of code from CommandGive:

 

            EntityItem entityitem = entityplayermp.dropPlayerItemWithRandomChoice(itemstack, false);
            entityitem.delayBeforeCanPickup = 0;
            entityitem.func_145797_a(entityplayermp.getCommandSenderName());