Regarding Continuous Downfall In Traffic After Server Change

What is the URL of your site?  

What SEO tools do you use?  

How do you measure site traffic?

My Site url- wapsr dot com
I use Attracta free seo tools provided by my hosting company hostgator
I checky site stat by inbuilt stat measurer in my cpanel of hosting comapny

First recommendation: Correct the HTML markup!
https://validator.w3.org/check?uri=http%3A%2F%2Fwapsr.com%2F&charset=%28detect+automatically%29&doctype=Inline&group=0

The <title> tag is very important, and it contains little "good" information and also has a key misspelled word.  Check all things like this.
<title> Wapsr.com:wapsr.in:Free Downlaod Hindi,Punjabi,Bhojpuri,English,Mp3 Songs,Videos</title>

Carrying advertisements for pornography and penis enlargement may also contribute to a decline in traffic, since many search engines would consider this to be potentially objectionable material and undesirable in their results.

I tend to trust Google Analytics for an accurate picture of web site traffic.  I would look at those statistics first, before anything else.

This is  a dodgy site - if you click on  any of the  the links on the home page
it opens lots of pop up windows with spam and downloads almac executable file onto my mac.

I had never insert pop up on my site...

when I click on any link on the site many windows popup
most of the windows fail but some open and  try to sell me stuff.
at the same time a download occurs and downloads a file called MACstreaming.dmg

Funky Guy:

If your site is producing pop-up windows and trying to force downloads onto client computers, there are only two possibilities.  Either you deliberately put these "features" into your site, or your site has been hacked and someone else put these "features" into your site.  In either case, when sites behave like this, they immediately get downgraded or omitted in search engine results.

Let's assume that you got hacked around the time of your server move.  The first thing you want to do is take the site down entirely; wipe out all of the scripts and data, and change your passwords.  Remove and recreate your database with new passwords.  Next, restore the site from your backups.  Notify HostGator that you believe your site has been hacked.
http://support.hostgator.com/articles/my-account-was-hacked

Going forward, this seems to be good guidance:
https://www.hostgator.com/blog/3-easy-steps-that-protect-your-website-from-hackers/

Some links regarding MACstreaming.dmg
https://apple.stackexchange.com/questions/250159/are-auto-downloaded-malicious-dmg-app-files-a-security-risk-if-they-are-never-o
https://www.reddit.com/r/applehelp/comments/5mkggd/little_box_keep_coming_up_called_macstreamingdmg/
https://www.intego.com/mac-security-blog/fake-flash-player-update-infects-mac-with-scareware/

The .dmg file is a disk image.  Do not click on it unless you know (for sure) what to expect.  The appearance  of something useful may be a masquerade; it does not protect you from malware.

Sir,
How Can This Happen i think my site is completely secure...because no one has yet complain about pop up, and if some has inserted it,it should open in every platform like windows,mac,android phones ,windows phone ... etc ..but on my pc or from any other pc no any popups are showing.