Vectors disappear

So I am having problem with my Item::return_all() as I call it in main.cpp. Earlier I tried return_all inside read_file() and for (auto data : example_item) loop printed data inside item_ correctly. What is the reason return_all() doesn't return (or atleast main.cpp doesn't print it) data inside item_if I call it in main? Or does the data inside item_ disappear due to some reason I don't know as my c++ knowledge is pretty limited.

Items.txt contains lines in format "1001:0:6".

main.cpp

#include "item.hh"
#include "functions.hh"

int main() {
   Item item;
   read_file("items.txt");
   std::vector<std::vector<int>> example_item = item.return_all();
   for (auto data : example_item){
       for (auto data2 : data){
           std::cout << data2 << std::endl;
       }
   }
}

item.hh

class Item {

  public:
    Item();
    void add_item(std::vector<int> item);
    std::vector<std::vector<int>> return_all();
    std::vector<int> return_item(const int& name) const;

  private:
    std::vector<std::vector<int>> item_; 
};

item.cpp

#include "item.hh"
#include "functions.hh"

Item::Item(){}

void Item::add_item(std::vector<int> item){
    item_.push_back(item);
}

std::vector<std::vector<int>> Item::return_all(){
    return item_;
}

std::vector<int> Item::return_item(const int& name) const {
    for (auto item : item_) {
        if (item.at(0) == name) {
            return item;
        }
    }
    return {};
}

functions.hh

void read_file(const std::string name);
std::vector<std::string> split(const std::string& string, char splitter);

functions.cpp

#include "item.hh"
#include "functions.hh"

void read_file(const std::string name){
       Item item;
       std::string line;
       std::ifstream myfile(name);
       if (myfile.is_open())
       {
         while (getline(myfile, line))
         {
             std::vector<std::string> field{};
             field = split(line, ':');
             int name = std::stoi(field.at(0));
             int type = std::stoi(field.at(1));
             int attr = std::stoi(field.at(2));
             std::vector<int> field_i = {name , type, attr};
             item.add_item(field_i);
         }
       }
         myfile.close();
   }

std::vector<std::string> split(const std::string& string, char splitter) {
    std::vector<std::string> fields{};
    std::string::size_type start_p{0};
    while ( true ) {
        std::string::size_type end_p{0};
        end_p = string.find(splitter, start_p);
        if ( end_p == std::string::npos ) {
            break;
        }
        std::string field{""};
        field = string.substr(start_p, end_p - start_p);
        fields.push_back(field);
        start_p = end_p + 1;
    }
    fields.push_back(string.substr(start_p));
    return fields;
}