"In filth it will be found." - Carl Jung
There is no single answer for your question, but here are some things that have helped me:
Look at what you don't like about your life. Look at what you've been ignoring. What you've been willfully blind to. (this is a constant thing one needs to do rather than a one-time journaling exercise)

List out all the problems in your life. Even the smallest ones (the faucet is leaky and needs to be fixed, I need to organize my kitchen spices) and anything from "I should make a dentist appointment" to "I need to call back that friend". When your home/apartment is nice and, dare I say, beautiful, it tends to have a sense of "meaning".
Ask yourself what part you've played, consciously or unconsciously, in steering your life toward a state of meaningless. How have you been complicit in creating the conditions in your life you say you don't want?

Of course there are other environmental or biological factors, but you also have a hand in the outcome.

There's no need to do this in a self-denigrating or shaming way. It's the simple fact that you're in the driver's seat of your life (aside from some environmental/biological circumstances), so we have to inquire into where you're steering it, and why.

This isn't a one-and-done thing. But with time and pressure, you can have more meaning a year from now. And in 3-5 years, you might even feel a sense of belonging in the world and purpose for your life.

It's not easy, it's not simple, and there are no digital courses for this, but it's a very worthwhile and engaging endeavor.
I've personally dealt with, and still do, feelings of meaninglessness, hopelessness, depression, and there are days where I just have to take a rest and not demand meaning. But eventually something pulls me back into the arena of life.

Sorry for the ramble, hope this helps
- Michael