Blank screen during installation of Windows 7 (Mid 2009 MacBook Pro)

Solution 1:

You can not us the Boot Camp Assistant, if you have both Yosemite and Catalina installed. You could do a clean install of Yosemite and then use the Boot Camp Assistant to install Windows 7. Apple intended the use of the optical drive when installing Windows 7 on your model Mac. If the optical drive is not an option, then you could try one of the legacy methods posted here a Ask Different. Some Macs can boot from an USB Windows 10 installer. If your Mac is capable of this, then you could use the CLI to install Windows 7 to your internal drive. Or, use the CLI to install Windows 10 instead.

You probably should install Windows to BIOS boot. If you also want macOS (OS X) installed, then you are going to need to use hybrid partitioning. This is where macOS (OS X) uses the GPT and Windows uses the MBR partition table. Installing (upgrading) to Windows 11 may not be possible, since Windows 11 is not supposed to be BIOS bootable.

The Apple website Install Windows 7 on your Mac using Boot Camp provides a link to the Boot Camp Support Software (Windows Support Software) for your model Mac.