What should I do when the references are not replying? I have worked in Germany for 2 years as a research assistant and then I moved to my home country and worked here for almost 4 years and published papers in reputed journals. Logically I think I should include the names of my current supervisors or the supervisors I have published works with.
But  Professor X (I am applying for a Ph.D. position) is originally from Germany, currently residing in Canada. He asked me to include three references from Germany. So I wrote the supervisors those I have worked under.

One of them had given LOR earlier in 2019 and it was very good (as he sent me once to check if everything was ok or not). I worked under him in 2014 and only for a month and we were on good terms. But now when I wrote him, he did not reply (its been 2 days)
Another one has also given me LOR when I was applying for another job. I worked under him for 4 months(I got the job that time in 2015). After that, we were not connected. He also did not reply.
The last one where I worked for 8 months ( in 2015) and learned most of my works which mean his LOR is the most valued one. But we did not finish on good terms. I mean we both have issues so I left that job at that time. After that, once I asked for a LOR from him, he only wrote a list of works that I learned from his lab, and nothing else (like good character or something that you usually need to write in a LOR). So I don't think his LOR will add anything positive to my application. But as  Professor X asked for their name, so I mailed him (the last one) too. Again he did not reply.

So basically I wrote three of my supervisors two days ago and asked for their permission if I can include their name in my application and none of them replied yet. Maybe things are difficult due to this pandemic.
In this situation what should I do? Should I write Professor X that I could not reach them? Or just send  Professor X the list of names? what if Professor X contacts them and they don't reply?
(I am restless because Professor X is waiting for my reply too)
Update: I have written to Professor X explaining the problems I am facing 3 days ago. And he did not reply to me yet. Should I write him again? or what can be a good step to take now?
People get loads of emails and it is very natural that some take a few days to reply. Also some emails may be missed or overlooked, so you can write again and say it's urgent. Normally such things should be done with a few weeks time if at all possible because answering to such requests is not the first thing on people's list.
If all else fails, try to contact somebody else. I'd avoid to give Professor X the list of names without having an answer from them. It doesn't look good to pass on such information without being authorised. You can ask Professor X for advice what to do without telling them names. Surely if Professor X is responsible for the tight time frame, they should have some understanding.