Avogadro 1.2 is no longer supported. In general on Windows, it has an issue with the Visual C++ Redistributable DLL (which can be downloaded here: Latest supported Visual C++ Redistributable downloads | Microsoft Learn)
As far as Avogadro 2, it would help to know what release you’re using. We’ve been trying to track down bugs for Windows users. One user reported success after editing the registry: Avogadro 2 does not start - #7 by whitfieldp
Another user reported that v1.97 worked but not newer versions: Avogadro 2 does not start - #10 by dschanz