The restore.dll supports the backup and maintenance features of the Microsoft System Management Server which guides users in a website recovery operation through Windows Recovery Expert tool.
If you're having an issue with your restore.dll file, the exact message displayed will vary depending on the application that is attempting to access it. Here are a few examples of messages you might receive:

Errors like the ones above can be an indication that the restore.dll file has been removed or changed in such a way that makes it impossible for your program to use.
Some users have been successful at finding a copy of the restore.dll file online and saving it into the appropriate folder on their PC (in this case, the C:\Program Files\SMSSETUP\BIN\I386). Get a replacement copy of the restore.dll file here
IMPORTANT NOTE: This means of adding the missing or corrupt dll file is not officially supported by Microsoft and should be performed with caution.
If you choose not to update drivers, any applications that access this file simply will stop functioning for you. Error messages of this sort are often only the first indicators that your PC's operating system is in need of some attention. Every time you install or remove an application from your computer, important files and registry entries are altered. In time, these small changes compound and Windows has difficulty making sense of the data. Unfortunately, correctly identifiying and remedying issues with a computer's operating system is a task usually far beyond the average user's skill level. If you are experiencing a “restore.dll missing” error, we highly recommend a free file health scan of your computer to look for other issues that may also be contributing computer's problems and go from there.
Many of our users have asked for more resources to assist with computer issues. If your problem is related to a zip password, we suggest using a product that can recover zip password.