Installing a Single DLL File is Often a Bandage for a Larger Problem
DLL files are only small parts of entire software programs. Often times, an error message that singles out an individual DLL file is only telling you part of the story. The particular error is often being generated only because it's the first problem the software is encountering, not because it's the single cause of the problem.
When you download and replace a DLL file from a DLL download site, you're often only solving one small part of a larger problem. Usually, the solution to the larger problem is to reinstall the entire software package that the DLL originated from.
Even if replacing a single DLL file fixes your immediate issue, additional problems tend to show up later, often as error messages notifying you of yet another missing DLL file. Save yourself a lot of time and energy and fix the problem right the first time.