I’m sorry to hear that. You are very much not alone – the most recent Helpful Content Update has hit a lot of bloggers hard. I have done a lot of research into this update. And from my research some clear patterns have emerged. First, this update is about Google wanting to reward high quality, helpful content. And second, this update has negatively affected sites that show poor UX and poor E-E-A-T / poor topical authority. I recommend you read the following articles which will guide you as to what you need to do in these areas:
https://www.productiveblogging.com/helpful-content-update/
https://www.productiveblogging.com/high-quality-content/
https://www.productiveblogging.com/improve-user-experience/
https://www.productiveblogging.com/eat/
https://www.productiveblogging.com/topical-authority/

Apart from this now my new blog post also take much time to index and doesn’t rank at top.

It is terrifying for me.

Please give me any tips specially related to indexing and ranking problem.