persian

I wonder if here is anyone who has an idea how in persian way
of writting is the prononciation of these words.So far i know
the persians do not use vowels and just consonants. In these
words trhe "-" should be a vowel, but which ?How we can see if
there is an "o", "a" or whatever?

N-n-d-r
V-n-n-t-r

The first word appears in the work of the persan writter
Gardizi (N-n-d-r) in the year 1050
The second word appears in the letter of kahan Josef ( I have
o ideea which kahan of which folk this one should be.)

regards