What rights do I have if I bought a product online and it didn't arrive?

It's not so much that you have to "force" him, but legally the seller is obligated to give you what you paid for or refund your money - that's covered by consumer protection laws pretty much everywhere. First thing would be to document everything: take screenshots of the purchase, the tracking, the messages you sent him, all of it. Then try to contact him through every possible means (email, social media, phone) and keep a record of each failed attempt. If after a week or two he doesn't respond, then you can escalate it through your payment platform (credit card, PayPal, whatever you used) by opening a dispute, or if the store is registered in your country, file a complaint with the consumer protection agency that applies.

Something similar happened to me last year when I ordered equipment for my photography sessions, and in the end the store had to refund me because the package got lost in the mail. If it's been 3 weeks with no response and the tracking doesn't show delivery, you have every right to demand a refund or a new shipment, it's the seller's responsibility to get the product to your door. Document everything (screenshots of the unanswered messages, the tracking, proof of payment) and if they don't respond, contact your payment platform or your country's consumer authority, that usually gets things moving pretty fast.

I ordered some bike tires a couple of months ago and the exact same thing happened - the tracking said delivered but it never showed up, and the seller disappeared. What I did was document everything (screenshots of the tracking, the ignored messages, dates) and filed a claim directly through the payment platform or the credit card I used, depending on where I bought it from. In my case the online store ended up responding the next day because the bank got involved. If 3 weeks have passed with no delivery or responses, you have every right to request a refund or reshipment, but you'll probably need to escalate the complaint outside of direct messages with the seller - either with the payment processor, the platform where you bought it, or if your country allows it, with the consumer protection authority. Sellers usually move fast when they see it's not just an informal complaint.