oleaut32.dll
This file is not a system component: windows itself, not a download. Restore it from the source that installed it rather than downloading a replacement.
If the file is already there and Windows still complains, read the message again: “entry point not found” is a different problem from a missing file, and installing the runtime again will not solve it.
And if the box says RUNDLL rather than naming a program, the fix runs the other way: something left an instruction behind pointing at a file that is meant to be gone, so restoring the file is the wrong move.
Do not download this DLL on its own
Searching for a missing DLL by name leads to sites that hand you that single file. It is one of the oldest and most effective malware delivery methods there is, and a system DLL from an unknown source is indistinguishable from a deliberately modified one. There is never a legitimate reason to obtain a runtime component that way.
The same goes for the tools that offer to do it for you: what a DLL repair tool can and cannot actually fix.
What it is
The OLE Automation library. It implements the data types that COM components pass between each other — BSTR strings, VARIANT values — and the plumbing that lets one program drive another. Visual Basic 6 applications, Office automation scripts and a great deal of older business software depend on it. It ships with Windows.
Where you see it: Old VB6 and COM applications, installers for line-of-business software, and errors mentioning regsvr32 or "class not registered" alongside the file name.
When this name appears the file is present on the machine essentially without exception, so the error is telling you about the component that failed to load, not about oleaut32 itself. In practice it is a registration or dependency problem: a COM component the application needs was never registered, was registered from a different folder, or was registered for the wrong architecture — the 32-bit and 64-bit COM registries are separate, and regsvr32 from a 64-bit terminal will not register a 32-bit component. The dangerous move here is the one the download sites suggest: fetching an old oleaut32.dll and running regsvr32 against it. Older builds of this library are not interchangeable with the current one, and overwriting the Windows copy can leave every COM application on the machine broken at once, not just the one you were trying to fix.
Why there is nothing to download here
There is no verified download we can offer for this one, because installing a file is not the fix. The steps above are what actually resolves it. That distinction matters: the sites ranking for this file name are selling a download that would not have helped even if it were safe.