How to register, unregister dll, ocx?

A DLL file, aka Dynamic Link Library, are files that contain functions used across multiple applications. Sometimes, you will run into a Windows problem where you have to register a DLL file on your computer. The following are steps:
1. First click on Start, then Run.

2. Now all you have to do to register a DLL file is to type in the regsvr32 command, followed by the path of the DLL file.

regsvr32 "C:\Windows\System32\mynew.dll"

3. Now click OK and you should get a confirmation message that the DLL has been registered successfully.

To unregister the dll, use the following syntax:

regsvr32 -u "C:\Windows\System32\mynew.dll"

In Windows Vista or Windows 7, if you are not able to register a DLL file and you end up getting an error message saying that the attempt to register the DLL file failed, you might want to disable UAC, User Account Control.

Turning off UAC has been known to fix the issue of failed attempts to register DLLs. Other issues could be that you need to right-click on the command prompt and choose Run as Administrator. Sometimes if the command prompt does not have administrator privileges, the register DLL command will fail.

Finally, you can try copying the regsvr32.exe file from an XP computer onto your Vista machine and then set the compatibility to Windows XP SP2.