Having too many assignments in your inbox is usually a sign that you've started falling behind. That's okay, it's not too late!
Set aside some time to properly go through your list, making sure that you mark all assignments that are no longer relevant as done.
If there are any assignments that you are still working on, plan when you would like to start working on them.
Do this until your inbox is empty. I know it seems like a lot of work right now, but once you are in control of your work and you know what you are doing, everything else will seem easier.