What exactly do you mean by "reactivate"?
What exactly are the symptoms of the problem that you're having?
When was everything working ok last?
When did you last buy a membership plan?
If it was more than 6 months ago then your SIM will most likely have been suspended and you'll need to contact 48 support to see if they can reverse the suspension.
If you need to contact them then see the links in my signature below.
