This file has been reported to be part of a spyware/malware/trojan. It is likely that the problem you are experiencing is linked directly to the spyware/malware/trojan rather than an actual missing DLL-file and the recommended course of action is to first locate/remove the Malware. We do not recommend downloading this file.
DLL-Files.com Support says:
msin32.dll is part of Tofger Trojan.
Manual removal is, technically, possible, but includes removing a large number of separate keys in the registry and a number of other actions including removal of autostart entries, appdata folders and individual .dll files. In short, We can't recommend anyone doing this on their own. Malwarebytes Anti Malware will kill this one for you.