If it was installed using Windows Installer (.MSI files), you can use the MsiGetComponentPath API:

    [DllImport("msi.dll", CharSet = CharSet.Unicode)]
    private static extern int MsiGetComponentPath(string szProduct, string szComponent, StringBuilder lpPathBuf, ref int pcchBuf);

Call it like this:

int len = 256;
StringBuilder sb = new StringBuilder(len);
MsiGetComponentPath(productCode, componentId, sb, ref len);