Cognizant Technology Solutions — status of offer letter

Address: 560066

Hi

I have been interviewed on september 23rd 2018, as per the hr discussion hr said that i am going to receive an offer letter within two weeks. I haven't heard from them yet. Can anyone help me out please.
Hr is'nt replying to my mails. Its been 4 months i am still awaiting for their response.
I have provide all the necessary documents, letter of authorization is also signed scanned and forwarded to them. One of the hr was in touch asking me to send few documents, and she addressed saying background check is going on and now when i ask about my status they aren't replying.