Fix Google Indexing for WordPress

My WordPress site was recently struck by a sudden de-indexing: Google now shows only two pages in its index. I have been bridging the gap with a paid indexing service, but that is obviously not a long-term solution... (Budget: ₹1500 - ₹12500 INR, Jobs: Analytics, Content Strategy, Link Building, PHP, SEO, Web Development, Website Optimization, WordPress)