Why does this return process id 0

the first issue you made was trying to make an ANSI string wide, you can't just cast it. There's a struct specifically for the wide version of PROCESSENTRY32 (PROCESSENTRY32W), and second when you're doing "==" you have to understand that you're comparing the pointers, the only time that would work is if the compiler optimized 2 constant strings to point to the same thing, in a dynamic scenario that wouldn't work.

Here's some improved code

#include <iostream>
#include <Windows.h>
#include <tlhelp32.h>
#include <tchar.h>

std::uint32_t get_proc_id(const std::wstring& name)
{
	auto result = 0ul;
	auto snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

	if (snapshot == INVALID_HANDLE_VALUE)
		return result;

	auto pe32w = PROCESSENTRY32W{};				// use the wide version of the struct
	pe32w.dwSize = sizeof(PROCESSENTRY32W);

	if (!Process32FirstW(snapshot, &pe32w))
		return CloseHandle(snapshot), result;

	while (Process32NextW(snapshot, &pe32w))
	{
		if (name == pe32w.szExeFile)			// use std::wstring's operator, not comparing pointers here
		{
			result = pe32w.th32ProcessID;
			break;
		}
	}

	CloseHandle(snapshot);
	return result;
}

int main()
{
	const auto pid = get_proc_id(L"explorer.exe");
	std::cout << pid;

	std::cin.get();
}

@0x90 c = 8 

@0x90 Thank you sorry for delayed response i have a job now lol

@0x90 your code is trash, do you even know C++ or are you just pretending to be something bigger than you actually are?

auto is bad practice in C++, and stop using snake_case

@dynamic_cast you're funny lol. 

You should've done some research before you made yourself look stupid. 

Even basic C++ programmers know AAA practice in C++, and why don't you take a look at the STL, it's snake_case for a reason, of course you think you're better than the libstdc++ devs, the people who literally define modern.