ftd2xx.dll
This file is not a system component: ftdi d2xx driver package. 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 FTDI D2XX library, which lets software talk directly to USB-to-serial chips made by FTDI. It arrives with the FTDI driver package, not with Windows.
Where you see it: Electronics tools, radio programming software, 3D printer utilities, industrial equipment and anything that speaks to hardware over a USB serial adapter.
Install the D2XX driver from FTDI themselves at ftdichip.com, matching the architecture of the program rather than the machine: a 32-bit tool needs the 32-bit ftd2xx.dll even on 64-bit Windows. Be careful with counterfeit adapters, which are widespread and can behave oddly with genuine drivers, and note that some applications expect the file in their own folder rather than in System32.
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.