rpcrt4.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.
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.
What it is
The Remote Procedure Call runtime, a core Windows component that almost every part of the system uses to communicate internally.
Where you see it: Application crashes naming rpcrt4.dll, and errors on machines with damaged system files.
Run "sfc /scannow" followed by "DISM /Online /Cleanup-Image /RestoreHealth". This file is tied to your Windows build and must never be replaced by hand: RPC underpins networking, printing and authentication, so a mismatched copy breaks far more than the program you were trying to run.
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.