It boots up into Windows, but then its a black screen

The computer boots up and sometimes it comes with the old windows recovery screen where it asks if you'd like to boot it in safe mode, ive tried all those safe mode options with no luck, only a black screen and the cursor which I can move. I think it might be related to the instance of Windows 7 thats booted on the drive considering the fact it does the same thing in multiple machines but thats coming from an amateur who has no idea what hes talking about and is probably going to be told is wrong. I also cant find an ISO for windows 7 since Microsoft says "its an OEM key, so nothing we can do" when they just give free handouts of Windows 10 ISOs. Mainly what I'm asking is do you know where I can get an ISO for Windows 7...