There are a lot things that could have gone wrong and it is hard to say something with 100% confidence without looking at the Analytics and Search Console.
Read this blog to discover what mostly goes wrong when traffic and ranking suddenly starts disappearing, https://www.upreports.com/blog/google-ranking-dropped-dramatically/

You have some on site stuff you need to resolve to start. There is over 50 pages that need some tune ups such as meta description touch ups, h1 headings, fix some duplicate stuff. I'd love to help fix these issues. Standing by if you wanna pop on a quick call to discuss further.

its look like you site not mobile optimized as google wants. After google Launched that mobile 1st indexed,,regular WordPress sites not use AMp and no upgrade their them according to Googles page index requirements you have to put much weight into those factors,, and again just like my other biddies said their some on page seos and tag issues too so make sure you get fix them

This might not be the main reason for your website positions going down, but it's something that will keep you from going up. Most of your visitors are from India, if you test a website speed for mobile users (with fast 3G connection) from India you'll see that it's rather slow https://webpagetest.org/result/191225_WA_972a2ca7545ba636e9a31c2dc3f0f7f3/ Site speed continuousely stated by Google as an important ranking factor that you definitely would take into consideration. You should aim to make your SpeedIndex at least twice better to rank high in Google (now it's 2.9s for the homepage). More information can be found here https://sabrinazeidan.com/tag/site-speed/

Without access to your Google Search Console, Google Tag Manager or Analytics, I can't give you an informed answer on how to improve your search ranking.

However, based on what I see from your website from running it through Google PageSpeed Insights, here's what I recommend for some quick wins on both the technical SEO side and the content site.

Your website page speed is quite slow so there's a lot you can do on the technical SEO side. When someone lands on your website, there are too many page requests which slows down loading time.

- You should remove any unused Javascript or CSS that interferes with loading of above-the-fold content. It looks like you have 228 requests, you might want to cut down some files or combine them.

- Reduce your image size with a tool like Smush. Large image sizes that aren't optimized will slow down your website.

- Google penalizes websites that aren't built for mobile. Based on my observations, your website is really lacking for mobile usage which will be a major roadblock for your ranking.

On the content side, it doesn't look like you have a robust keyword strategy based on the content I've read. You have roughly 30-40 organic keywords driving visitors to your website. Your website is quite a niche so I can't see you ranking for massive amounts of volume. On the good side, your content is pretty robust especially with your APKs and How-To's

- I'd recommend doing more keyword research to inform your content strategy. You can write keyword-rich and mobile-optimized content for your audience which includes additional links internally and externally to other websites.

Also, there are a few things you should consider:
- Fixing broken links on the website so nothing leads to a 404 error.
- Aim for "Position Zero" on Google. Content snippets that get featured for quality answers are great for increasing website traffic.
- Use H1 and H2 headers in your content.
- Optimize images for search.
- Improve website experience for users,

get creative, try anything and everything and be your own life coach