I’ll assume you still want to do web development. JavaScript, HTML, and CSS are still the most valuable things to learn, but my goodness they’ve changed in the past 15 years. There are a number of free learning options, https://teamtreehouse.com/, https://theodinproject.com/, https://www.codecademy.com/ just to name a few. If I were you I’d learn those three languages and spend some time learning one of the popular frameworks, such as react or angular, just to familiarize myself with the tools most companies use. That will be more than enough to become employable again.

You’re going to do great, lots of developers these days don’t have a CS degree, and there’s even a sizable percentage who have no degree at all, so you’re already ahead of the game. Don’t listen to imposter syndrome.

One more bit of advice, start networking either online or in person. Join discord servers, meetup.com groups, whatever so you can start interacting in the community again. You’ll learn about jobs faster that way, the community will help you along the way, and you’ll end up helping them too.