Q: no service is apearing on screen on 4s

Follow the 3R's- if a restart does not solve your problem proceed

User troubleshooting is:

1. restart, ie power off/on,

2. reset  http://support.apple.com/kb/HT1430,

3. restore from backup, restore as new device. http://support.apple.com/kb/HT1414

You can try popping out the SIM card and putting it back in.

Remove or switch the SIM card in your iPhone or iPad - Apple Support