Cheat Engine

[Stylo]

Go old school

[atom0s]

Look into how to hook an IAT/EAT entry to do pointer hooks rather than full blown detours, which is what it looks like you are trying to do.

[atom0s]

There are tons of examples of doing it online, just Google for it.

[atom0s]

You are doing things entirely wrong, more or less because you don't understand what you are doing.

Firstly, DispatchMessageA is an API call, it is not going to be specifically at address 0x029F8654. It is an API so it is going to be within its parents module space. For DispatchMessageA, its within User32.dll. If you want to get its address specifically, use GetProcAddress.

If you want to hook it you are going to need to mimic what detours do, or create a hook-hop type of hook.
(Also known as a mid-function hook.)

Doing that, you place a jump at the start of the API (or mid-function hence the name) and jump to your own code. You need to restore the original code, realign the stack as needed, do whatever you want to in your hook, realign the stack again if needed and jump back if desired.

Here is a small tutorial someone did explaining mid-function hooks somewhat:
https://www.unknowncheats.me/forum/c-and-c/67884-mid-function-hook-big-deal.html

There are a handful of other tutorials on the net explaining this in better detail, I recommend you read up on what you are trying to do first as you are doing it wrong.

[atom0s]

[Dark Byte]

When you call DispatchMessageA you are calling the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
Which calls the hooked version of dispatchMessageA, which jumps to DispatchMessageA_Hook
till you run out of stack and crash

You need to store the original code somewhere, with some extra code so it jumps back to after the hook. Then call that instead of DispatchMessageA

Tip: Add a disassembler to your code to figure out the size of the instructions you're overwriting and where to place the jmp back