Lost phone and WhatsApp issue I lost my phone and I have some contacts on WhatsApp which I don't have anywhere else.

Is there any way to get those contacts? I have already deactivated my SIM card.

Can I get the data back?
Sorry to say, but there is no or alternate way for this.

I had lost my phone and i was having some contacts on whatsapp which i dont have anywhere else.

This thing is a bit wrong, because Whatsapp would use your own phonebook to check which of your contacts have whatsapp. It won't let you add any user to your stock pile by just adding them as friends.

Is there any way to reach to that contacts .

If there is a backup of the data on Google servers, then there might be an option. But I don't think that would work! So there is no way to get them back.

I know this is not a technical question concerned with android

True, but actually this is a site for the Android questions. So you're in the correct place. To ask how to get data, but now about how to get data from a lost phone. Thats impossible.
Possible things that would help
Well these are not the helping materials, but just in case to remind you that, in the settings, did you check backup my data. If so, try signing in Google from other phone, it might give you some data.
Not sure of this but you said the contacts were no where else but on whatsapp, so try signing in to whatsapp again, maybe they still have those contacts for you!