Before you can go forward, you need to rewind.
It is easy to get stuck in the past when you recall everything through rose-tinted glasses. However, every one of those memories you had also had a negative side. Consider each one of them and look for the reasons why you would rather put the memories behind and move on, and how those good times have made you a better person.
Then do the same with your current circumstances - make a list of the things you have learnt about yourself from your situation. Once you understand why the past has happened and the present is happening, all of it (both the positive and negative from the past and present) become part of you.
Then you can use all that wisdom as the stepping stone to move into the lovely future that is waiting for you - and you have to trust me on this ;-)
We know already that the world is changing fast, and it is never going to go back to where it was. The issue is not how we get to how things were, but how we cope with what we have in our lives today and move forward.