On Windows 10 64-bit, there's two versions of the .DLL. One is in System32 and the other is in SysWOW64.
If the file is missing from system32, you might want to investigate that with
Using System File Checker in Windows 10[
^]
Your machine seems to have more issues that that if you have to put System32 and SysWOW64 back into the PATH environment variable.