A little more information please. Without the extra information you are asking a question like 'how long is a piece of string?'

Can you access your data on the unit?
When you log in via the web interface what does it say about the status of the drives?
Do you have a full backup of all your data on the unit?
Is it a single two drives and how did you set them up (RAID 1, JBOD, STANDARD etc.)?
Now to answer your questions?
If the drives do in fact need to be reformatted this MUST be done in the unit itself, no other computers are required other than to allow you to log in to the web interface.