Lightroom black screen

This is about Lightroom 5 That is now not working slideshow,Black screen I have had a conversation with Adobe assistant they tell me that Lightroom 5 is now discontinued you can not download it and there is no help they can give . I thought if you bought software on disk with a serial number box that this should work correctly, but it seems not there is no help from Adobe they say move to Lightroom classic at a monthly subscription. One more thing people are still selling Lightroom 4 and 5 on eBay for hundreds of pounds watch out on support Charles