There are many similar threads to this and the NC thing is always a contentious issue. I personally favour the NC thing but it depends on your circumstances. Was it a mutual break, did you leave her or did she leave you? Do you want to reconcile? Does your relationship have problems which will need to be sorted out if you did reconcile?
Hypothetically if she initiated the split NC is probably best as she may want to be left alone to move on with her life. Just remember this is just as hard on her as it is on you and just because she isn't contacting you doesn't mean she isn't missing you. People deal with things in different ways.
Some people are drains and some are radiators... Keep clear of the drains and hug the radiators!