what should i do if my mobile carrier nokia does not helps me deactivating the service of my lost mobile?

Nokia is a manufacturer of phones, not a cell carrier. In the USA the largest cell carriers are Verizon, AT&T, and Sprint. Are you contacting the correct company? Or is the problem that it belonged to your employer and you’re not authorized to have them deactivate it? Have you explained the situation to them? You may just have to bite the bullet and report it to the powers that be at your job.

I’m just curious—did you try calling the number as I had suggested in your previous question, to see if someone else found the phone and answers? We were able to get my ex-bf’s phone back after he lost it by doing that.

If you are going to purchase a new phone have them deactivate it when you move the # to the new phone

Since Nokia is not a mobile carrier, you need to identify who is your carrier.

Once you’ve done that, call said company or visit one of their local stores and proceed to ask for help.

Best of luck, mate!