C++ Hashing Passwords - simple algorithm using rand()
Structure
Okay, let's start with the basic overall structure of the function: it's, frankly, not very good. It (unnecessarily) depends on a number of outside variables--from its perspective, essentially globals.
There's no good reason that this couldn't be a nice, pure function--i.e., take an input parameter, do the hash, return a result. No reference to anything outside the function at all.
int HashPassword(std::string const &amp;Combine) { 
    unsigned int hash = 0;

    const unsigned int VALUE = Combine.length();
    for (auto Letter : Combine)
    {
        srand(VALUE*Letter);
        hash += 33 + rand() % 92;
    }
    return hash;
}

Naming
Some of the names are pretty good (e.g., Letter, HashPassword) but others (e.g., VALUE, Combine) seem like they're open to some improvement. I can see how you came up with Combine, but that doesn't really make it a good name. VALUE is so generic that it's probably best to avoid it except (perhaps) in something like a class that represents some number, where the VALUE of the object has a fairly obvious meaning.
Magic numbers
The 33 and 92 are a couple of examples of magic numbers. These generally lead to code that's difficult to read (at best).
Security
This hash function provides approximately what's usually referred to as &quot;kid sister&quot; level security. If you have a kid sister, this might be about enough to keep her fooled--but only if she's not very bright or fairly quickly bored.
The most obvious problem is that this just generates a value from each byte, then adds those values together. This means nobody really needs to know your actual password--at most they only need to care about the letters that make up the password. For example, HashPassword(&quot;ABC&quot;), and HashPassword(&quot;CAB&quot;) both produce exactly the same result.
So, to get the right result, we don't really even need to guess their password--we just need to guess some characters that produce the right result--and since nearly every input in the right range maps to a unique result, it doesn't take a lot to come up with a usable result either. For example, let's consider a result of 628. Each input produces a result from 32 to 124, so we might want to use, say, seven characters in a password. So, let's start by computing the result for seven repetitions of each character in the most common range:
for (int i = '0'; i &lt; 'z'; i++) {
    std::string in(7, (char)i);
    std::cout &lt;&lt; &quot;in: &quot; &lt;&lt; in[0] &lt;&lt; &quot;, hash: &quot; &lt;&lt; HashPassword(in) / 7 &lt;&lt; &quot;\n&quot;;
}

So, our smallest result is 32--a little more than the &quot;28&quot; that's left over if we divide 628 by 6, so we want something that produces a result a little less than 100. A quick glance shows that 1 produces a result of 87--that'll probably do. So, if we start with 111111, we should get a result of 6 * 87 = 522. That gives us 106 left over. Another glance through the table shows that &quot;R&quot; gives 106, so an input of 111111R should give us 628. A quick run with     std::cout &lt;&lt; HashPassword(&quot;111111R&quot;); verifies that it does exactly that.
In case it seems like I hand-picked something that would be easy, I'll point out that I actually got the 628 from hashing &quot;Password&quot;--so to find 111111R, I really did start over from scratch--and I didn't even have to work hard at it--my first attempt worked out easily.
For another approach, I could have started with 5 of something. Let's say 'j', which gives 102. 5 x 102 = 510. I want two more characters to make up the remainder, so for my next character I want to pick something fairly small. Let's say _, which produces 35. With the previous 510, we get 545. A quick subtraction shows that we need 83 more, and a quick search shows that &quot;M&quot; produces 83, so jjjjj_M would work as well (and a quick test verifies that yes, it also produces 628).
Bottom line: from a security viewpoint, this is so weak that it's open to question whether it really even qualifies as &quot;kid sister&quot; level, or if it's too weak to even qualify for that level of &quot;security&quot;.