I �m not sure of your context, but I �ll see if I can help. 
 
I �m not used to knowing --- "used to" means "accustomed" --- so, also correct would be "I �m not accustomed to knowing" 
 
"knowing" here is used as a noun. 
 
I �m (I am)  not used to milk for breakfast.  I usually just have coffee.
I �m  (I am) not used to dancing before dinner. I usually just watch tv. 
I �m  (I am) not used to waking up late.  I usually get up at sunrise. 
I �m (I am)  not used to walking to work.  I usually take the bus. 
I�m (I am) not used to knowing the answers. I still think I should ask for help!
 
used to + ____________ (noun, infinitive) 
 
or another way to look at it -- 
 
used to + _______________ (thing or activity) 
 
 
"Used to" can also mean something that you did in the past but you no longer do. 
 
I used to live in Shanghai but now I live in Beijing. 
I used to know the people in that building but they don�t live there now. 
I used to be young but now I am old. 
I used to run every day but now I work too much overtime.  -------- Things that were normal in the past, but no longer happen. 
 
 
used to + ____________ (verb)  
 
Can you see the difference? 
 
Hope this helps.