Send an email to MSU Library Mendeley Support at Mendeley@lib.msu.edu.. Please provide as much detail as you can about the issue, including which kind of computer you're using (PC or Mac) and which browser. We'll get back to you as soon as we can.
Help Guides and Videos are available from the Mendeley Guides and Tutorials page.
If you are into the development side of Mendeley, (APIs) check out the Mendeley API Developers page.