How do I fix iPhone showing 'no service'?

DavidUfomba wrote:

Thanks but I’m not correctly in the united state because I changed location

Well that would surely explain it. If you still have an active cellular plan in the US and are traveling internationally temporarily, you would need to roam or use a separate SIM. If you have moved internationally permanently, you need to cancel your plan with your previous carrier and find a new one in your region. Otherwise that would show the No Service status.

Follow the steps in this article: If you see SOS, No Service, or Searching on your iPhone or iPad - Apple Support

Another unconventional fix that used to work for me was calling someone for at least a few seconds (attempting a call can sometimes trigger a re-scan of nearby towers, which might re-establish a connection)

If you aren’t in a remote, off-the-grid location, then this would indicate an issue with your carrier or your account with them. As a result you need to contact them for help.