You have to measure the refrigerant pressure.
There is a tool called pressure gauge specifically made for checking AC system.
There is no way to determine from your information given to us, all we know is that the AC is not working.
If you ask here, I suspect, you don't have the tool.
So you need to buy it or bring it to someone who has the tool and knowledge to use it.
That someone can be a mechanic shop or a friend.
So, if there is no pressure, why?
Is there leaks, or the compressor gave up or the clutch in the compressor give up, etc.
For leaks, we need to investigate where.
You can use sniffer or put dye on the refrigerant then use a special uv light to see it.