Answer Description

DLL not found errors should never be remediated by downloading the missing DLL. A missing DLL can be a symptom of a greater issue, but more pressingly DLL download sites can deploy malware via the downloads or open security loopholes on your PC. You should quarantine the PC, verifying that there has been no intrusion or compromise of the system before proceeding with investigating the missing DLL's root cause.

Wikipedia

Dynamic-link library (DLL) is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems. These libraries usually have the file extension DLL, OCX (for libraries containing ActiveX controls), or DRV (for legacy system drivers). The file formats for DLLs are the same as for Windows EXE files – that is, Portable Executable (PE) for 32-bit and 64-bit Windows, and New Executable (NE) for 16-bit Windows. As with EXEs, DLLs can contain code, data, and resources, in any combination. Data files with the same file format as a DLL, but with different file extensions and possibly containing only resource sections, can be called resource DLLs. Examples of such DLLs include icon libraries, sometimes having the extension ICL, and font files, having the extensions FON and FOT.