Because individual .msi files like ica_x64.msi are not distributed separately by Corel, the standard fix is to download the full installer for the 2020 suite.
Windows’ installer service remembers the original source path of the MSI files. If you installed Corel 2020 from a downloaded Setup.exe (which you then deleted), or from a DVD (which you ejected), Windows will ask you to locate ica x64.msi again. ica x64.msi corel 2020 download