msvcrt.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 original Microsoft C Runtime, part of Windows since the 1990s and still shipped with every version. It is a protected system file and no publisher distributes it separately.
Where you see it: Very old software, and machines where a "DLL fixer" or a cracked program overwrote the real file with its own copy.
This is the file most commonly offered by DLL download sites, and it is the one you should least accept from them. It lives in System32 on every Windows install, so a missing or broken msvcrt.dll means system damage, not an absent download. Run "sfc /scannow" and then "DISM /Online /Cleanup-Image /RestoreHealth" from an elevated terminal. Note also that msvcrt.dll is not the modern runtime: software built with Visual Studio 2015 or later needs the Visual C++ redistributable instead, which is a different file entirely.
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.