The Elder Scrolls V: Skyrim main Quest game breaking bug

I am currently trying to finish the quest 'Alduin's Bane'. I have retrieved the Elder Scroll, visited my buddy in the mountain and initiated the time warp. I watch the three guys kill the first dragon then we all sit and wait for Alduin to turn up so I can learn the dragonrend shout but he never does. I have left the game running for over an hour and the NPCs just stand 'in combat' and 4 lesser looking dragons permanently fly around the top of the mountain. I have reloaded from previous saves and re-opened the game etc but the quest is just totally bugged and I can’t continue past it. Do you have any suggestion for this?

You can try to reload the game and see if that can solve the issue for you. I hope that this will solve the problem for you. Please reply if that does not help you.

You have to make use of the Elder Scroll item from your inventory and after that watch the vision. When they say the dragon is approaching he comes right away so if you wait more than a minute that is too long and reload the save.

I had this glitch too. After watching the scene 7 or 8 times it finally worked, however, now I am in the fight with Alduin and cannot do any damage to him. When I get him on the ground with Dragonrend and swing my weapon, there's no sound effect of him being hit and his health remains untouched. I tried hitting Parthaanax, and I can damage him just fine. I really need your help for this. I can't continue the game without a fix.

If none of the solutions helps you then you can try to by reinstalling the game. If there is some issue with the installed files of the game then reinstalling will surely solve the problem for you.