I graduated in 2017 and my course doesn't exist anymore and my course leader/module leaders have mostly left. The only member of staff that would have been there when I was still there is a lecturer that taught me 2 modules in 1st and 2nd year, and I wouldn't say knows me.
What do I do?
I assume you were part of a school within the university?
If there is still a head of the school, then they should be able to write a generic-ish reference based on past module grades (which they should still have on file)