Please contact the Assessments team first to discuss your options. You may be able to apply for a visa extension which will cover your reassessment, or you may be able to apply to switch to repeat with attendance, subject to certain conditions including timetabled engagement.
There will be a fee for repeating with attendance, which you can check with Finance Services. If you are not eligible to stay in the UK to complete your reassessment, you may be able to make arrangements to do your reassessment from your home country.
We advise you to follow the steps which you have received from assessment board. You can also check some more information here (If your study situation changes | Manchester Metropolitan University (mmu.ac.uk)) and you can also contact the team at the Student Hub if you have additional questions.