Further to Anna's reply...
One thing you could do is check in mynewman to see what modules you are registered onto.
(Go to mynewman and click the Students tab on the left hand side. Also check your timetable.)
That would establish whether you are properly registered. If not it is Student Records who deal with enrolment, but hopefully Anna's email on your behalf will sort it out.
The other thing that crosses my mind is whether this is caused by a distinction between resitting and retaking.
If you are retaking, yes, you should see your module on Moodle. However, if you are resitting, you will not be on this year's modules and you should click the link to last year's Moodle and revisit the modules there.
I hope this gets sorted out quickly for you.
Head of e-Learning