I've run Lightroom 6 on Windows 7 Pro for 6 years. Yesterday, Lightroom suddenly stopped opening. It freezes in mid-launch. I uninstalled and reinstalled just now. Same problem. I have not installed new programs in the past week so I can not guess what is suddenly interfering.
Hmm, there have been at least a couple other reports recently of similar symptoms with LR 6 on Windows (at least one was Windows 10, I think). You might search this forum and lightroomqueen.com's forum for simiilar reports.