Macbook air charger not working?

Then, at this point, I believe you have the following three choices, and will depend on how long you have had this laptop:

1. If you purchased an AppleCare+ plan with your laptop within the last three years, or if you didn't but the laptop is under a year old, you can have an Apple Technician examine both the adapter and cable to see if either/both have a manufacturing defect. Should that be the case you may find that you can get a replacement for little or no cost to you.
2. If, in item 1, neither are true, then you would need to purchase replacements.
3. Alternately, if you have the proper test equipment, you can verify whether or not either are non-functiional.

Which exact power adapter and charging cable are you trying to use with your MacBook Air (MBA)?

This MBA model comes with an Apple 30W USB-C power adapter. Is that what you have?

What exactly have you tried, so far yourself, to resolve this issue so that we don't offer potential solutions that may not have already worked for you?