Most programs use some form of library files to hold common routines used by multiple parts of the program. These files typically have the extension .DLL or .OCX and are distributed with programs that need them. Rarely, one needs to be re-registered with Windows.
When a program installs a library (DLL or OCX) file the program’s install routine will typically “register” the file with the system. This process tells the system the libraries in the file are available for more than one program to use. (Some DLL or OCX files are self-registering.)
Sometimes, if multiple programs are using a DLL or OCX file the system does not know about all of them. In this case, if you uninstall one of the programs its uninstall routine may delete the library in question not knowing that another program needs it. When this is done the library’s registration with the system no longer applies. And, if you just copy the DLL or OCX file back where it came from the system may not recognize it even if it’s in the proper place. While this is rare, when this happens you may need to “register” the library file manually.
You can find the full details about how to use the REGSVR32.EXE file at this Microsoft link…
The process is non-trivial so you should study the referenced page quite closely if you are going to attempt to register a library file. Indeed, it just might be easier to reinstall the application in question and let its installer take care of the regsitration process as part of the install.
In summary, if you choose to manually register a library file you will have to restart your computer in command prompt mode (called DOS mode in some cases). Once there, you will have to issue a command of the form…
Regsvr32 [/u] [/n] [/i[:cmdline]] dllname
It’s possible this procedure may fail in which case you may need information from the developer of the library.
I guess the bottom line recommendation from Computer Knowledge would be to avoid this process if at all possible.
Where Do You Get DLL Files?
As mentioned above, all of the library files you need should have been provided by the programs that require them. In the rare instance that you need one and can’t find it on the Website of the program in question you might try…