If you or your driver can't see any modules this is almost always because either the driver (or you) are not assigned to a group, or you've made a group and unassigned all the modules. It can happen when you delete a group that has drivers assigned to it and they are not assigned to any other group. In this image, the third driver won't see any modules as no group is assigned.

Assigning the driver to a group

Click on Manage > Drivers and Courses then Course and driver options > Manage Drivers. This lists all your drivers. Find the driver in question and click Edit. Choose a group and save it.

Re-enabling modules in a group.

Check out this article on assigning modules. You need to be the account holder.

Driver can't see a course, despite doing it before

This is almost always because the driver has two separate logins - one might be an email, one is a username, e.g. firstname.lastname.