Why won't anyone respond to me on the repeater?

This is a complicated question because there are many facets to this question. Let's break it down. In the end, there is one answer that can answer all of your questions, talk to your local club or a local ham. They can help you make sure everything is configured correctly and it's working. There are many variables that people on the internet can't answer that a local person can.

Most repeaters require a PL tone in order to communicate through it. Make sure you have the right receive frequency, the right transmit frequency, and the right tone.

Sometimes, you are just plain too far away. Try different locations, drive closer to it and test it there. You should get some sort of feedback if you are hitting the repeater.

The repeater directories aren't always up to date. You might want to talk to a local club to find out the most up to date information.

Many times, people aren't listening. Try at different times like morning and evening drive times, noon, or weekends.

Maybe the repeater is a digital one and it's actually busy, but it's on digital.

If you hear traffic, but no one responds to you, check your tone and transmit frequency to make sure it's right. It is also possible, they are ignoring you if they don't know you. My hams are introverts and tend to be shy. Introduce yourself, say “{callsign} I'm a new ham and looking for my first contact.”

If you have tried everything else and no response or can't find help. This usually gets someone's attention. It is not required, but if you say “CQ CQ CQ {your call sign}” for about 30 seconds someone may respond with “you aren't supposed to do that on repeaters”. Guess what? You got a response and you now know it works. The rest is up to you.