Let's try this a different way...
The error message probably says "Re-installing the application may fix this problem." You do not reinstall the rtl120.bpl application for it is not an application - it is a file. So you can't reinstall rtl120.bpl.
You need to reinstall the application that uses the rtl120.bpl file. Some application you have installed needs the rtl120.bpl file and the file is missing.
Since the file has nothing to do with XP, it has to do with some third party application that has been installed on your computer. Since there are probably billions of third party softwares, who know which of those applications use rtl120.bpl. Hundreds?
Thousands? Meelions?
And you are the only one that knows what third party programs you have installed on your computer.
If the file is missing, it was probably quarantined (effectively deleted) by your unspecified antivirus/antimalware application. If whatever that is has a quarantine folder, you may be able to restore the file from there. Otherwise you are going to have
to figure out which program you have installed that uses it and reinstall that program
The rtl120.bpl file is from Embarcadero Technologies and gets installed on your system from third party software packages such as:
AVG (their PC Analyzer component)
TuneUp Utilities
Advanced System Care (ASC)
(others)
For example, if you have Advanced System Care installed, the message may look like this:
ASC.exe - Unable to Locate Component
This application has failed to start because rtl120.bpl was not found. Re-installing the application may fix this problem.
From that message, you can see that the complaining program is ASC.exe and that belongs to Advanced System Care, so you would uninstall and reinstall ASC.
There may be other third party applications that install the file, but if you don't provide the exact error message in it's entirety nobody is going to be able to help you. And since the file has absolutely nothing to do with Microsoft Windows, maybe nobody
in the Microsoft community will be able to help you without more information (like the complete error message).
You could use msconfig and through a process of elimination perhaps figure it out.