I'm missing an important document, and have no idea what I can do to retrieve it.

I have been a Dropbox  user since 2011. I'm a professor and have always assumed my files were safe. Last week, one disappeared - and it is a whole academic publication. That is my original intellectual property. Losing that work has significant implications for my professional reputation and career. I have already missed the deadline for submission.

I have opened a ticket.I have done the extensive trouble shooting with multiple agents. They transfer me to email, then send me requests to grant permission. The link they said is invalid. Day go by, There are no responses to my emails. I open new chat. They tell me to wait. One consultant said my case was escalated. Another said it's closed/solved. I just need my work back. I can't really believe a company that you may a subscription to firstly fails on the grounds of keeping your work safe, and then just gives you the runaround. I'm no closer to a solution, which is severely impacting my health and mental health