I have a claimed minecraft server, but yesterday it stopped working and it says that my server is offline.. it stopped working suddenly.. i don't know why.
It's a hosted server.
http://www.gametracker.com/server_info/23.235.224.5:25565/

Here are my cumulative suggestions I typically provide for minecraft:

1. You confirmed your server is up-to-date.
2. You confirmed your server is not running any query plugins, like minequery.
3. The query port is correct.
4. You've opened the query port in any network software (firewall, router) for TCP/UDP.
5. You've setup your server.properties.
6. You've tried without mods that are known to break the server query, namely MCPC+ and bungeecord.
7. You've confirmed you are not blocking GT:

208.167.241.190
208.167.241.185
208.167.241.186
208.167.241.183
208.167.241.189
108.61.78.147
108.61.78.148
108.61.78.149
108.61.78.150

I verified all of these.
The problem is that the server suddenly stopped working on gametracker but i didn't modify anything.

Your hosting company might blocked foreign traffic.

It's a gametracker problem.
They don't block foreign traffic.

I can confirm it is not a GameTracker problem. Your server is not responding to the query.